diff --git a/pkgs/swift2objc/lib/src/ast/_core/interfaces/declaration.dart b/pkgs/swift2objc/lib/src/ast/_core/interfaces/declaration.dart
index 4c237c8ba..34b356af4 100644
--- a/pkgs/swift2objc/lib/src/ast/_core/interfaces/declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/_core/interfaces/declaration.dart
@@ -2,10 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import '../../ast_node.dart';
 import '../shared/referred_type.dart';
 
 /// A common interface for all Swift entities declarations.
-abstract interface class Declaration {
+abstract interface class Declaration implements AstNode {
   abstract final String id;
   abstract final String name;
 }
diff --git a/pkgs/swift2objc/lib/src/ast/_core/interfaces/nestable_declaration.dart b/pkgs/swift2objc/lib/src/ast/_core/interfaces/nestable_declaration.dart
index b857a3b68..e38ae4a5f 100644
--- a/pkgs/swift2objc/lib/src/ast/_core/interfaces/nestable_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/_core/interfaces/nestable_declaration.dart
@@ -2,10 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import '../../ast_node.dart';
 import 'declaration.dart';
 
 /// A Swift entity that can be nested inside other declarations.
-abstract interface class NestableDeclaration implements Declaration {
+abstract interface class NestableDeclaration implements Declaration, AstNode {
   abstract NestableDeclaration? nestingParent;
   abstract final List<NestableDeclaration> nestedDeclarations;
 }
diff --git a/pkgs/swift2objc/lib/src/ast/_core/shared/parameter.dart b/pkgs/swift2objc/lib/src/ast/_core/shared/parameter.dart
index 19b4421fc..768134b6f 100644
--- a/pkgs/swift2objc/lib/src/ast/_core/shared/parameter.dart
+++ b/pkgs/swift2objc/lib/src/ast/_core/shared/parameter.dart
@@ -2,10 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import '../../ast_node.dart';
 import 'referred_type.dart';
 
 /// Describes parameters of function-like entities (e.g methods).
-class Parameter {
+class Parameter extends AstNode {
   String name;
   String? internalName;
   ReferredType type;
@@ -18,4 +19,10 @@ class Parameter {
 
   @override
   String toString() => '$name $internalName: $type';
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visit(type);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/_core/shared/referred_type.dart b/pkgs/swift2objc/lib/src/ast/_core/shared/referred_type.dart
index 56f50b72d..9bbd4080b 100644
--- a/pkgs/swift2objc/lib/src/ast/_core/shared/referred_type.dart
+++ b/pkgs/swift2objc/lib/src/ast/_core/shared/referred_type.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import '../../ast_node.dart';
 import '../interfaces/declaration.dart';
 import '../interfaces/nestable_declaration.dart';
 import '../interfaces/objc_annotatable.dart';
@@ -9,7 +10,7 @@ import '../interfaces/objc_annotatable.dart';
 /// Describes a type reference in declaration of Swift
 /// entities (e.g a method return type).
 /// See `DeclaredType` and `GenericType` for concrete implementation.
-sealed class ReferredType {
+sealed class ReferredType extends AstNode {
   abstract final bool isObjCRepresentable;
 
   abstract final String swiftType;
@@ -17,10 +18,14 @@ sealed class ReferredType {
   bool sameAs(ReferredType other);
 
   const ReferredType();
+
+  @override
+  void visit(Visitation visitation) => visitation.visitReferredType(this);
 }
 
 /// Describes a reference of a declared type (user-defined or built-in).
-class DeclaredType<T extends Declaration> implements ReferredType {
+class DeclaredType<T extends Declaration> extends AstNode
+    implements ReferredType {
   final String id;
 
   String get name {
@@ -52,11 +57,21 @@ class DeclaredType<T extends Declaration> implements ReferredType {
 
   @override
   String toString() => name;
+
+  @override
+  void visit(Visitation visitation) => visitation.visitDeclaredType(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visit(declaration);
+    visitor.visitAll(typeParams);
+  }
 }
 
 /// Describes a reference of a generic type
 /// (e.g a method return type `T` within a generic class).
-class GenericType implements ReferredType {
+class GenericType extends AstNode implements ReferredType {
   final String id;
 
   final String name;
@@ -77,10 +92,13 @@ class GenericType implements ReferredType {
 
   @override
   String toString() => name;
+
+  @override
+  void visit(Visitation visitation) => visitation.visitGenericType(this);
 }
 
 /// An optional type, like Dart's nullable types. Eg `String?`.
-class OptionalType implements ReferredType {
+class OptionalType extends AstNode implements ReferredType {
   final ReferredType child;
 
   @override
@@ -97,4 +115,13 @@ class OptionalType implements ReferredType {
 
   @override
   String toString() => swiftType;
+
+  @override
+  void visit(Visitation visitation) => visitation.visitOptionalType(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visit(child);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/ast_node.dart b/pkgs/swift2objc/lib/src/ast/ast_node.dart
new file mode 100644
index 000000000..7e13c55af
--- /dev/null
+++ b/pkgs/swift2objc/lib/src/ast/ast_node.dart
@@ -0,0 +1,104 @@
+// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'visitor.dart';
+export 'visitor.dart';
+
+/// Base interface of all AST nodes, including types, bindings, and other
+/// elements.
+///
+/// Anything that we might want to visit should be an [AstNode]. Most things
+/// that contain [AstNode]s should also be [AstNode]s (except for top level
+/// objects like `Library` that are in charge of running the visitors, or
+/// caching objects like `BindingsIndex` or `Writer`).
+///
+/// The AST and visitor infrastucture is pretty complicated, so here are the
+/// common tasks you might need to do as a maintainer:
+///
+/// ## Creating a new type of [AstNode]
+///
+/// For example, adding a class `Foo` which extends `Bar`, which somewhere up
+/// the heirarchy extends [AstNode]:
+///
+/// 1. Write your `Foo` class and extend `Bar`.
+/// 2. If `Foo` has children (ie fields that are [AstNode]s), override the
+///    `visitChildren` method. Make sure to call `super.visitChildren`
+///    so that `Bar`'s children are also visited. If all `Foo`'s children
+///    are inherited from `Bar`, it's not necessary to implement this method.
+///   ```dart
+///   @override
+///   void visitChildren(Visitor visitor) {
+///     super.visitChildren(visitor);
+///     visitor.visit(myChild);
+///     visitor.visitAll(myChildList);
+///   }
+///   ```
+///
+/// Since there are many AstNodes that no one is ever going to need to visit,
+/// we're using a lazy-loading policy for the `visitFoo` method. When someone
+/// wants to write a [Visitation] that is specific to `Foo` (ie not covered by
+/// `visitBar`), that's when the `visitFoo` function will be added.
+///
+/// The steps are essentially the same to change an existing class to extend
+/// [AstNode].
+///
+/// ## Creating a new [Visitation]
+///
+/// 1. Write the visitation as a class that extends [Visitation]. The class may
+///    be stateful, but shouldn't care about the order that nodes are visited.
+///    This class may mutate the nodes, but shouldn't assume that all children
+///    have finished being visited when processing the parent.
+/// 2. Override the visit methods for whichever type you're interested in.
+///   ```dart
+///   @override
+///   void visitFoo(Foo node) {
+///     // Typically this method would visit the children, but that's not always
+///     // what you want to do.
+///     node.visitChildren(this);
+///
+///     // It's not necessarily true that all the children have finished being
+///     // visited at this point.
+///
+///     // The rest of this method can edit the node in-place.
+///   }
+///   ```
+/// 3. If you want to visit `Foo` specifically (and not its supertypes), but
+///    there's no `visitFoo` method to override, add a `visitFoo` method to
+///    [Visitation]. Assuming `Foo` extends `Bar`, `visitFoo` should delegate to
+///    `visitBar`:
+///   `void visitFoo(Foo node) => visitBar(node);`
+/// 4. Then add a `visit` method to `Foo` that invokes `visitFoo`:
+///   ```dart
+///   @override
+///   void visit(Visitation visitation) => visitation.visitFoo(this);
+///   ```
+/// 5. Repeat 3 and 4 for `Bar` and any other supertypes as necessary.
+///
+/// ## Running a [Visitation]
+///
+/// 1. Construct the [Visitation] and wrap it in a [Visitor]:
+///   `final visitor = Visitor(MyFancyVisitation(1, 2, 3));`
+/// 2. Invoke the [Visitor] on the root nodes of the AST:
+///   ```dart
+///   visitor.visit(someRootNode);
+///   visitor.visitAll(listOfRootNodes);
+///   ```
+abstract class AstNode {
+  const AstNode();
+
+  /// Visit this node. All this method does is delegate to the visit method that
+  /// is specific to this type of node.
+  ///
+  /// This method should be implemented for a particular type of [AstNode] only
+  /// when there are [Visitation]s that need to visit that type specifically.
+  void visit(Visitation visitation) => visitation.visitAstNode(this);
+
+  /// Visit this node's children. This is the method that actually understands
+  /// the structure of the node. It should invoke [Visitor.visit] etc on all the
+  /// node's children.
+  ///
+  /// This method must be implemented if the node has children. The
+  /// implementation should call `super.visitChildren(visitor);`.
+  void visitChildren(Visitor visitor) {}
+}
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/built_in/built_in_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/built_in/built_in_declaration.dart
index 9c75ba42f..cfee5d6a0 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/built_in/built_in_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/built_in/built_in_declaration.dart
@@ -4,17 +4,11 @@
 
 import '../../_core/interfaces/declaration.dart';
 import '../../_core/interfaces/objc_annotatable.dart';
+import '../../ast_node.dart';
 
 /// Describes a built-in Swift type (e.g Int, String, etc).
-enum BuiltInDeclaration implements Declaration, ObjCAnnotatable {
-  swiftNSObject(id: 'c:objc(cs)NSObject', name: 'NSObject'),
-  swiftString(id: 's:SS', name: 'String'),
-  swiftInt(id: 's:Si', name: 'Int'),
-  swiftFloat(id: 's:Sf', name: 'Float'),
-  swiftDouble(id: 's:Sd', name: 'Double'),
-  swiftBool(id: 's:Sb', name: 'Bool'),
-  swiftVoid(id: 's:s4Voida', name: 'Void');
-
+class BuiltInDeclaration extends AstNode
+    implements Declaration, ObjCAnnotatable {
   @override
   final String id;
 
@@ -28,12 +22,34 @@ enum BuiltInDeclaration implements Declaration, ObjCAnnotatable {
     required this.id,
     required this.name,
   });
+
+  @override
+  void visit(Visitation visitation) => visitation.visitBuiltInDeclaration(this);
 }
 
-final objectType = BuiltInDeclaration.swiftNSObject.asDeclaredType;
-final stringType = BuiltInDeclaration.swiftString.asDeclaredType;
-final intType = BuiltInDeclaration.swiftInt.asDeclaredType;
-final floatType = BuiltInDeclaration.swiftFloat.asDeclaredType;
-final doubleType = BuiltInDeclaration.swiftDouble.asDeclaredType;
-final boolType = BuiltInDeclaration.swiftBool.asDeclaredType;
-final voidType = BuiltInDeclaration.swiftVoid.asDeclaredType;
+const _objectDecl =
+    BuiltInDeclaration(id: 'c:objc(cs)NSObject', name: 'NSObject');
+const _stringDecl = BuiltInDeclaration(id: 's:SS', name: 'String');
+const _intDecl = BuiltInDeclaration(id: 's:Si', name: 'Int');
+const _floatDecl = BuiltInDeclaration(id: 's:Sf', name: 'Float');
+const _doubleDecl = BuiltInDeclaration(id: 's:Sd', name: 'Double');
+const _boolDecl = BuiltInDeclaration(id: 's:Sb', name: 'Bool');
+const _voidDecl = BuiltInDeclaration(id: 's:s4Voida', name: 'Void');
+
+const builtInDeclarations = [
+  _objectDecl,
+  _stringDecl,
+  _intDecl,
+  _floatDecl,
+  _doubleDecl,
+  _boolDecl,
+  _voidDecl,
+];
+
+final objectType = _objectDecl.asDeclaredType;
+final stringType = _stringDecl.asDeclaredType;
+final intType = _intDecl.asDeclaredType;
+final floatType = _floatDecl.asDeclaredType;
+final doubleType = _doubleDecl.asDeclaredType;
+final boolType = _boolDecl.asDeclaredType;
+final voidType = _voidDecl.asDeclaredType;
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/compounds/class_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/compounds/class_declaration.dart
index 9bf875b91..42dedb96e 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/compounds/class_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/compounds/class_declaration.dart
@@ -7,6 +7,7 @@ import '../../_core/interfaces/declaration.dart';
 import '../../_core/interfaces/nestable_declaration.dart';
 import '../../_core/interfaces/objc_annotatable.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 import '../built_in/built_in_declaration.dart';
 import 'members/initializer_declaration.dart';
 import 'members/method_declaration.dart';
@@ -14,7 +15,8 @@ import 'members/property_declaration.dart';
 import 'protocol_declaration.dart';
 
 /// Describes the declaration of a Swift class.
-class ClassDeclaration implements CompoundDeclaration, ObjCAnnotatable {
+class ClassDeclaration extends AstNode
+    implements CompoundDeclaration, ObjCAnnotatable {
   @override
   String id;
 
@@ -75,5 +77,23 @@ class ClassDeclaration implements CompoundDeclaration, ObjCAnnotatable {
     this.initializers = const [],
   }) : assert(superClass == null ||
             superClass.declaration is ClassDeclaration ||
-            superClass.declaration == BuiltInDeclaration.swiftNSObject);
+            superClass.sameAs(objectType));
+
+  @override
+  void visit(Visitation visitation) => visitation.visitClassDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(properties);
+    visitor.visitAll(methods);
+    visitor.visitAll(conformedProtocols);
+    visitor.visitAll(typeParams);
+    visitor.visit(superClass);
+    visitor.visit(wrappedInstance);
+    visitor.visit(wrapperInitializer);
+    visitor.visitAll(initializers);
+    visitor.visit(nestingParent);
+    visitor.visitAll(nestedDeclarations);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/initializer_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/initializer_declaration.dart
index d7c5431b3..ce4bf5685 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/initializer_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/initializer_declaration.dart
@@ -10,9 +10,10 @@ import '../../../_core/interfaces/objc_annotatable.dart';
 import '../../../_core/interfaces/overridable.dart';
 import '../../../_core/interfaces/parameterizable.dart';
 import '../../../_core/shared/parameter.dart';
+import '../../../ast_node.dart';
 
 /// Describes an initializer for a Swift compound entity (e.g, class, structs)
-class InitializerDeclaration
+class InitializerDeclaration extends AstNode
     implements
         Declaration,
         Executable,
@@ -62,4 +63,14 @@ class InitializerDeclaration
     required this.async,
     required this.isFailable,
   });
+
+  @override
+  void visit(Visitation visitation) =>
+      visitation.visitInitializerDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(params);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/method_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/method_declaration.dart
index c7567fe9c..604b31350 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/method_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/method_declaration.dart
@@ -7,10 +7,11 @@ import '../../../_core/interfaces/objc_annotatable.dart';
 import '../../../_core/interfaces/overridable.dart';
 import '../../../_core/shared/parameter.dart';
 import '../../../_core/shared/referred_type.dart';
+import '../../../ast_node.dart';
 
 /// Describes a method declaration for a Swift compound entity
 /// (e.g, class, structs)
-class MethodDeclaration
+class MethodDeclaration extends AstNode
     implements FunctionDeclaration, ObjCAnnotatable, Overridable {
   @override
   String id;
@@ -62,4 +63,15 @@ class MethodDeclaration
     this.throws = false,
     this.async = false,
   }) : assert(!isStatic || !isOverriding);
+
+  @override
+  void visit(Visitation visitation) => visitation.visitMethodDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(params);
+    visitor.visitAll(typeParams);
+    visitor.visit(returnType);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/property_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/property_declaration.dart
index 6bcced2d9..297cdb8b5 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/property_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/compounds/members/property_declaration.dart
@@ -6,10 +6,12 @@ import '../../../_core/interfaces/executable.dart';
 import '../../../_core/interfaces/objc_annotatable.dart';
 import '../../../_core/interfaces/variable_declaration.dart';
 import '../../../_core/shared/referred_type.dart';
+import '../../../ast_node.dart';
 
 /// Describes a property declaration for a Swift compound entity
 /// (e.g, class, structs)
-class PropertyDeclaration implements VariableDeclaration, ObjCAnnotatable {
+class PropertyDeclaration extends AstNode
+    implements VariableDeclaration, ObjCAnnotatable {
   @override
   String id;
 
@@ -52,6 +54,16 @@ class PropertyDeclaration implements VariableDeclaration, ObjCAnnotatable {
     this.async = false,
   })  : assert(!(isConstant && hasSetter)),
         assert(!(hasSetter && throws));
+
+  @override
+  void visit(Visitation visitation) =>
+      visitation.visitPropertyDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visit(type);
+  }
 }
 
 class PropertyStatements implements Executable {
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/compounds/protocol_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/compounds/protocol_declaration.dart
index 197b5ee6d..5ae946781 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/compounds/protocol_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/compounds/protocol_declaration.dart
@@ -5,12 +5,13 @@
 import '../../_core/interfaces/compound_declaration.dart';
 import '../../_core/interfaces/nestable_declaration.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 import 'members/initializer_declaration.dart';
 import 'members/method_declaration.dart';
 import 'members/property_declaration.dart';
 
 /// Describes the declaration of a Swift protocol.
-class ProtocolDeclaration implements CompoundDeclaration {
+class ProtocolDeclaration extends AstNode implements CompoundDeclaration {
   @override
   String id;
 
@@ -49,4 +50,20 @@ class ProtocolDeclaration implements CompoundDeclaration {
     this.nestingParent,
     this.nestedDeclarations = const [],
   });
+
+  @override
+  void visit(Visitation visitation) =>
+      visitation.visitProtocolDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(properties);
+    visitor.visitAll(methods);
+    visitor.visitAll(conformedProtocols);
+    visitor.visitAll(typeParams);
+    visitor.visitAll(initializers);
+    visitor.visit(nestingParent);
+    visitor.visitAll(nestedDeclarations);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/compounds/struct_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/compounds/struct_declaration.dart
index ba157ff29..8dc19cbae 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/compounds/struct_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/compounds/struct_declaration.dart
@@ -5,13 +5,14 @@
 import '../../_core/interfaces/compound_declaration.dart';
 import '../../_core/interfaces/nestable_declaration.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 import 'members/initializer_declaration.dart';
 import 'members/method_declaration.dart';
 import 'members/property_declaration.dart';
 import 'protocol_declaration.dart';
 
 /// Describes the declaration of a Swift struct.
-class StructDeclaration implements CompoundDeclaration {
+class StructDeclaration extends AstNode implements CompoundDeclaration {
   @override
   String id;
 
@@ -50,4 +51,19 @@ class StructDeclaration implements CompoundDeclaration {
     this.nestingParent,
     this.nestedDeclarations = const [],
   });
+
+  @override
+  void visit(Visitation visitation) => visitation.visitStructDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(properties);
+    visitor.visitAll(methods);
+    visitor.visitAll(conformedProtocols);
+    visitor.visitAll(typeParams);
+    visitor.visitAll(initializers);
+    visitor.visit(nestingParent);
+    visitor.visitAll(nestedDeclarations);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/enums/associated_value_enum_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/enums/associated_value_enum_declaration.dart
index d8f374354..b27eca124 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/enums/associated_value_enum_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/enums/associated_value_enum_declaration.dart
@@ -7,10 +7,12 @@ import '../../_core/interfaces/nestable_declaration.dart';
 import '../../_core/interfaces/parameterizable.dart';
 import '../../_core/shared/parameter.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 import '../compounds/protocol_declaration.dart';
 
 /// Describes the declaration of a Swift enum with associated values.
-class AssociatedValueEnumDeclaration implements EnumDeclaration {
+class AssociatedValueEnumDeclaration extends AstNode
+    implements EnumDeclaration {
   @override
   String id;
 
@@ -41,10 +43,25 @@ class AssociatedValueEnumDeclaration implements EnumDeclaration {
     this.nestingParent,
     this.nestedDeclarations = const [],
   });
+
+  @override
+  void visit(Visitation visitation) =>
+      visitation.visitAssociatedValueEnumDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(cases);
+    visitor.visitAll(typeParams);
+    visitor.visitAll(conformedProtocols);
+    visitor.visit(nestingParent);
+    visitor.visitAll(nestedDeclarations);
+  }
 }
 
 /// Describes the declaration of a Swift enum case with associated values.
-class AssociatedValueEnumCase implements EnumCase, Parameterizable {
+class AssociatedValueEnumCase extends AstNode
+    implements EnumCase, Parameterizable {
   @override
   String id;
 
@@ -59,10 +76,16 @@ class AssociatedValueEnumCase implements EnumCase, Parameterizable {
     required this.name,
     required this.params,
   });
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(params);
+  }
 }
 
 /// Describes an associated value of an Swift enum case.
-class AssociatedValueParam implements Parameter {
+class AssociatedValueParam extends AstNode implements Parameter {
   @override
   String name;
 
@@ -76,4 +99,10 @@ class AssociatedValueParam implements Parameter {
     required this.name,
     required this.type,
   });
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visit(type);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/enums/normal_enum_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/enums/normal_enum_declaration.dart
index cd4e05b70..c021c1883 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/enums/normal_enum_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/enums/normal_enum_declaration.dart
@@ -5,11 +5,12 @@
 import '../../_core/interfaces/enum_declaration.dart';
 import '../../_core/interfaces/nestable_declaration.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 import '../compounds/protocol_declaration.dart';
 
 /// Describes the declaration of a basic Swift enum
 /// (i.e with no raw values or associated values).
-class NormalEnumDeclaration implements EnumDeclaration {
+class NormalEnumDeclaration extends AstNode implements EnumDeclaration {
   @override
   String id;
 
@@ -40,11 +41,25 @@ class NormalEnumDeclaration implements EnumDeclaration {
     this.nestingParent,
     this.nestedDeclarations = const [],
   });
+
+  @override
+  void visit(Visitation visitation) =>
+      visitation.visitNormalEnumDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(cases);
+    visitor.visitAll(typeParams);
+    visitor.visitAll(conformedProtocols);
+    visitor.visit(nestingParent);
+    visitor.visitAll(nestedDeclarations);
+  }
 }
 
 /// Describes the declaration of a basic Swift enum case
 /// (i.e with no raw values or associated values).
-class NormalEnumCase implements EnumCase {
+class NormalEnumCase extends AstNode implements EnumCase {
   @override
   String id;
 
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/enums/raw_value_enum_declaration.dart b/pkgs/swift2objc/lib/src/ast/declarations/enums/raw_value_enum_declaration.dart
index 7774a02d8..b52494b25 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/enums/raw_value_enum_declaration.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/enums/raw_value_enum_declaration.dart
@@ -6,10 +6,12 @@ import '../../_core/interfaces/enum_declaration.dart';
 import '../../_core/interfaces/nestable_declaration.dart';
 import '../../_core/interfaces/objc_annotatable.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 import '../compounds/protocol_declaration.dart';
 
 /// Describes the declaration of a Swift enum with raw values.
-class RawValueEnumDeclaration<T> implements EnumDeclaration, ObjCAnnotatable {
+class RawValueEnumDeclaration<T> extends AstNode
+    implements EnumDeclaration, ObjCAnnotatable {
   @override
   String id;
 
@@ -47,10 +49,25 @@ class RawValueEnumDeclaration<T> implements EnumDeclaration, ObjCAnnotatable {
     this.nestingParent,
     this.nestedDeclarations = const [],
   });
+
+  @override
+  void visit(Visitation visitation) =>
+      visitation.visitRawValueEnumDeclaration(this);
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(cases);
+    visitor.visitAll(typeParams);
+    visitor.visitAll(conformedProtocols);
+    visitor.visit(nestingParent);
+    visitor.visitAll(nestedDeclarations);
+    visitor.visit(rawValueType);
+  }
 }
 
 /// Describes the declaration of a Swift enum case with a raw value of type `T`.
-class RawValueEnumCase<T> implements EnumCase {
+class RawValueEnumCase<T> extends AstNode implements EnumCase {
   @override
   String id;
 
diff --git a/pkgs/swift2objc/lib/src/ast/declarations/globals/globals.dart b/pkgs/swift2objc/lib/src/ast/declarations/globals/globals.dart
index c06cc5077..e8497bbd9 100644
--- a/pkgs/swift2objc/lib/src/ast/declarations/globals/globals.dart
+++ b/pkgs/swift2objc/lib/src/ast/declarations/globals/globals.dart
@@ -6,6 +6,7 @@ import '../../_core/interfaces/function_declaration.dart';
 import '../../_core/interfaces/variable_declaration.dart';
 import '../../_core/shared/parameter.dart';
 import '../../_core/shared/referred_type.dart';
+import '../../ast_node.dart';
 
 /// A container for globally defined values (i.e variables & constants)
 /// and functions.
@@ -20,7 +21,7 @@ class Globals {
 }
 
 /// Describes a globally defined function.
-class GlobalFunctionDeclaration implements FunctionDeclaration {
+class GlobalFunctionDeclaration extends AstNode implements FunctionDeclaration {
   @override
   String id;
 
@@ -55,10 +56,18 @@ class GlobalFunctionDeclaration implements FunctionDeclaration {
     this.throws = false,
     this.async = false,
   });
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visitAll(params);
+    visitor.visitAll(typeParams);
+    visitor.visit(returnType);
+  }
 }
 
 /// Describes a globally defined values (i.e variable/constant).
-class GlobalVariableDeclaration implements VariableDeclaration {
+class GlobalVariableDeclaration extends AstNode implements VariableDeclaration {
   @override
   String id;
 
@@ -85,4 +94,10 @@ class GlobalVariableDeclaration implements VariableDeclaration {
     required this.throws,
     required this.async,
   }) : assert(!(throws && !isConstant));
+
+  @override
+  void visitChildren(Visitor visitor) {
+    super.visitChildren(visitor);
+    visitor.visit(type);
+  }
 }
diff --git a/pkgs/swift2objc/lib/src/ast/visitor.dart b/pkgs/swift2objc/lib/src/ast/visitor.dart
new file mode 100644
index 000000000..5c0e0f258
--- /dev/null
+++ b/pkgs/swift2objc/lib/src/ast/visitor.dart
@@ -0,0 +1,121 @@
+// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:logging/logging.dart';
+
+import '../ast/_core/interfaces/compound_declaration.dart';
+import '../ast/_core/interfaces/declaration.dart';
+import '../ast/_core/interfaces/enum_declaration.dart';
+import '../ast/_core/interfaces/function_declaration.dart';
+import '../ast/_core/interfaces/variable_declaration.dart';
+import '../ast/_core/shared/referred_type.dart';
+import '../ast/ast_node.dart';
+import '../ast/declarations/built_in/built_in_declaration.dart';
+import '../ast/declarations/compounds/class_declaration.dart';
+import '../ast/declarations/compounds/members/initializer_declaration.dart';
+import '../ast/declarations/compounds/members/method_declaration.dart';
+import '../ast/declarations/compounds/members/property_declaration.dart';
+import '../ast/declarations/compounds/protocol_declaration.dart';
+import '../ast/declarations/compounds/struct_declaration.dart';
+import '../ast/declarations/enums/associated_value_enum_declaration.dart';
+import '../ast/declarations/enums/normal_enum_declaration.dart';
+import '../ast/declarations/enums/raw_value_enum_declaration.dart';
+import '../ast/declarations/globals/globals.dart';
+
+final _logger = Logger('swift2objc.visitor');
+
+/// Wrapper around [Visitation] to be used by callers.
+final class Visitor {
+  Visitor(this._visitation, {bool debug = false}) : _debug = debug {
+    _visitation.visitor = this;
+  }
+
+  final Visitation _visitation;
+  final _seen = <AstNode>{};
+  final bool _debug;
+  int _indentLevel = 0;
+
+  /// Visits a node.
+  void visit(AstNode? node) {
+    if (node == null) return;
+    if (_debug) _logger.info('${'  ' * _indentLevel++}$node');
+    if (!_seen.contains(node)) {
+      _seen.add(node);
+      node.visit(_visitation);
+    }
+    if (_debug) --_indentLevel;
+  }
+
+  /// Helper method for visiting an iterable of nodes.
+  void visitAll(Iterable<AstNode> nodes) {
+    for (final node in nodes) {
+      visit(node);
+    }
+  }
+}
+
+/// Base class for all AST visitations.
+///
+/// Callers should wrap their [Visitation] in a [Visitor] and invoke its
+/// methods, instead of interacting directly with the [Visitation]. This
+/// distinction is why [Visitor] and [Visitation] are seperate classes.
+///
+/// The `visitFoo` methods in this class should reflect the inheritance
+/// heirarchy of all AstNodes. Eg `visitChild` should default to calling
+/// `visitBase` which should default to calling `visitAstNode`.
+///
+/// Implementers should implement the specific visit methods for each node type
+/// they care about. Any visit methods not implemented will default to calling
+/// `node.visitChildren`, which visits the node's children but otherwise doesn't
+/// alter the node itself.
+abstract class Visitation {
+  late final Visitor visitor;
+
+  void visitReferredType(ReferredType node) => visitAstNode(node);
+  void visitDeclaredType(DeclaredType node) => visitReferredType(node);
+  void visitGenericType(GenericType node) => visitReferredType(node);
+  void visitOptionalType(OptionalType node) => visitReferredType(node);
+  void visitDeclaration(Declaration node) => visitAstNode(node);
+  void visitBuiltInDeclaration(BuiltInDeclaration node) =>
+      visitDeclaration(node);
+  void visitInitializerDeclaration(InitializerDeclaration node) =>
+      visitDeclaration(node);
+  void visitFunctionDeclaration(FunctionDeclaration node) =>
+      visitDeclaration(node);
+  void visitMethodDeclaration(MethodDeclaration node) =>
+      visitFunctionDeclaration(node);
+  void visitGlobalFunctionDeclaration(GlobalFunctionDeclaration node) =>
+      visitFunctionDeclaration(node);
+  void visitVariableDeclaration(VariableDeclaration node) =>
+      visitDeclaration(node);
+  void visitPropertyDeclaration(PropertyDeclaration node) =>
+      visitVariableDeclaration(node);
+  void visitGlobalVariableDeclaration(GlobalVariableDeclaration node) =>
+      visitVariableDeclaration(node);
+  void visitCompoundDeclaration(CompoundDeclaration node) =>
+      visitDeclaration(node);
+  void visitClassDeclaration(ClassDeclaration node) =>
+      visitCompoundDeclaration(node);
+  void visitProtocolDeclaration(ProtocolDeclaration node) =>
+      visitCompoundDeclaration(node);
+  void visitStructDeclaration(StructDeclaration node) =>
+      visitCompoundDeclaration(node);
+  void visitEnumDeclaration(EnumDeclaration node) => visitDeclaration(node);
+  void visitAssociatedValueEnumDeclaration(
+          AssociatedValueEnumDeclaration node) =>
+      visitEnumDeclaration(node);
+  void visitNormalEnumDeclaration(NormalEnumDeclaration node) =>
+      visitEnumDeclaration(node);
+  void visitRawValueEnumDeclaration<T>(RawValueEnumDeclaration<T> node) =>
+      visitEnumDeclaration(node);
+
+  /// Default behavior for all visit methods.
+  void visitAstNode(AstNode node) => node..visitChildren(visitor);
+}
+
+T visit<T extends Visitation>(T visitation, Iterable<AstNode> roots,
+    {bool debug = false}) {
+  Visitor(visitation, debug: debug).visitAll(roots);
+  return visitation;
+}
diff --git a/pkgs/swift2objc/lib/src/parser/parsers/parse_declarations.dart b/pkgs/swift2objc/lib/src/parser/parsers/parse_declarations.dart
index 36b74c4f4..af3f8e443 100644
--- a/pkgs/swift2objc/lib/src/parser/parsers/parse_declarations.dart
+++ b/pkgs/swift2objc/lib/src/parser/parsers/parse_declarations.dart
@@ -59,7 +59,7 @@ Declaration parseDeclaration(
     _ => throw Exception(
         'Symbol of type $symbolType is not implemented yet.',
       ),
-  } as Declaration;
+  };
 
   return parsedSymbol.declaration!;
 }
diff --git a/pkgs/swift2objc/lib/src/parser/parsers/parse_symbols_map.dart b/pkgs/swift2objc/lib/src/parser/parsers/parse_symbols_map.dart
index 72df7de07..e98bdc68b 100644
--- a/pkgs/swift2objc/lib/src/parser/parsers/parse_symbols_map.dart
+++ b/pkgs/swift2objc/lib/src/parser/parsers/parse_symbols_map.dart
@@ -9,7 +9,7 @@ import '../_core/utils.dart';
 
 ParsedSymbolsMap parseSymbolsMap(Json symbolgraphJson) {
   final parsedSymbols = {
-    for (final decl in BuiltInDeclaration.values)
+    for (final decl in builtInDeclarations)
       decl.id: ParsedSymbol(json: Json(null), declaration: decl)
   };
 
diff --git a/pkgs/swift2objc/lib/src/transformer/_core/dependencies.dart b/pkgs/swift2objc/lib/src/transformer/_core/dependencies.dart
index 30e693d88..032367ac8 100644
--- a/pkgs/swift2objc/lib/src/transformer/_core/dependencies.dart
+++ b/pkgs/swift2objc/lib/src/transformer/_core/dependencies.dart
@@ -1,259 +1,32 @@
-import '../../ast/_core/interfaces/declaration.dart';
-import '../../ast/_core/interfaces/enum_declaration.dart';
-import '../../ast/_core/interfaces/function_declaration.dart';
-import '../../ast/_core/interfaces/variable_declaration.dart';
-import '../../ast/_core/shared/parameter.dart';
-import '../../ast/_core/shared/referred_type.dart';
-import '../../ast/declarations/compounds/class_declaration.dart';
-import '../../ast/declarations/compounds/members/initializer_declaration.dart';
-import '../../ast/declarations/compounds/protocol_declaration.dart';
-import '../../ast/declarations/compounds/struct_declaration.dart';
-
-// TODO(https://github.com/dart-lang/native/issues/1814): Type restrictions have not yet been implemented in system
-class DependencyVisitor {
-  final Iterable<Declaration> declarations;
-  Set<Declaration> visitedDeclarations = {};
-
-  DependencyVisitor(this.declarations);
-
-  Set<Declaration> visit(Declaration dec) {
-    final dependencies = <Declaration>{};
-
-    Iterable<Declaration> d = [dec];
-
-    while (true) {
-      final deps = d.fold<Set<String>>(
-          {}, (previous, element) => previous.union(visitDeclaration(element)));
-      final depDecls = declarations.where((d) => deps.contains(d.id));
-      if (depDecls.isEmpty ||
-          (dependencies.union(depDecls.toSet()).length) ==
-              dependencies.length) {
-        break;
-      } else {
-        dependencies.addAll(depDecls);
-        d = depDecls;
-      }
-    }
-
-    visitedDeclarations.addAll(dependencies);
-
-    return dependencies;
-  }
-
-  Set<String> visitDeclaration(Declaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // switch between declarations
-    if (decl is ClassDeclaration) {
-      visitClass(decl, cont);
-    } else if (decl is ProtocolDeclaration) {
-      visitProtocol(decl, cont);
-    } else if (decl is StructDeclaration) {
-      visitStruct(decl, cont);
-    } else if (decl is FunctionDeclaration) {
-      visitFunction(decl, cont);
-    } else if (decl is VariableDeclaration) {
-      visitVariable(decl, cont);
-    } else if (decl is EnumDeclaration) {
-      visitEnum(decl, cont);
-    }
-
-    return cont;
-  }
-
-  Set<String> visitEnum(EnumDeclaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // visit nested declarations
-    for (var n in decl.nestedDeclarations) {
-      visitDeclaration(n, cont);
-    }
-
-    // visit protocols
-    for (var p in decl.conformedProtocols) {
-      visitProtocol(p.declaration, cont);
-    }
-
-    // ensure generic types do not enter
-    cont.removeWhere(
-        (t) => decl.typeParams.map((type) => type.name).contains(t));
-
-    return cont;
-  }
-
-  Set<String> visitStruct(StructDeclaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // visit variables
-    for (var d in decl.properties) {
-      visitVariable(d, cont);
-    }
-
-    // visit methods
-    for (var m in decl.methods) {
-      visitFunction(m, cont);
-    }
-
-    // visit initializers
-    for (var i in decl.initializers) {
-      visitInitializer(i, cont);
-    }
-
-    // visit nested declarations
-    for (var n in decl.nestedDeclarations) {
-      visitDeclaration(n, cont);
-    }
-
-    // visit protocols
-    for (var p in decl.conformedProtocols) {
-      visitProtocol(p.declaration, cont);
-    }
-
-    // ensure generic types do not enter
-    cont.removeWhere(
-        (t) => decl.typeParams.map((type) => type.name).contains(t));
-
-    return cont;
-  }
-
-  Set<String> visitClass(ClassDeclaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // visit variables
-    for (var d in decl.properties) {
-      visitVariable(d, cont);
-    }
+// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
 
-    // visit methods
-    for (var m in decl.methods) {
-      visitFunction(m, cont);
-    }
-
-    // visit initializers
-    for (var i in decl.initializers) {
-      visitInitializer(i, cont);
-    }
-
-    // visit super if any
-    if (decl.superClass != null) {
-      visitDeclaration(decl.superClass!.declaration, cont);
-    }
-
-    // visit nested declarations
-    for (var n in decl.nestedDeclarations) {
-      visitDeclaration(n, cont);
-    }
-
-    // visit protocols
-    for (var p in decl.conformedProtocols) {
-      visitProtocol(p.declaration, cont);
-    }
-
-    // ensure generic types do not enter
-    cont.removeWhere(
-        (t) => decl.typeParams.map((type) => type.name).contains(t));
-
-    return cont;
-  }
-
-  Set<String> visitProtocol(ProtocolDeclaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // visit variables
-    for (var d in decl.properties) {
-      visitVariable(d, cont);
-    }
-
-    // visit methods
-    for (var m in decl.methods) {
-      visitFunction(m, cont);
-    }
-
-    // visit initializers
-    for (var i in decl.initializers) {
-      visitInitializer(i, cont);
-    }
-
-    // visit nested declarations
-    for (var n in decl.nestedDeclarations) {
-      visitDeclaration(n, cont);
-    }
-
-    // visit protocols
-    for (var p in decl.conformedProtocols) {
-      visitProtocol(p.declaration, cont);
-    }
-
-    // ensure generic types do not enter
-    cont.removeWhere(
-        (t) => decl.typeParams.map((type) => type.name).contains(t));
-
-    return cont;
-  }
-
-  Set<String> visitInitializer(InitializerDeclaration decl,
-      [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // similar to `visitMethod`, except no return type
-    for (var p in decl.params) {
-      visitParameter(p, cont);
-    }
-
-    return cont;
-  }
-
-  Set<String> visitFunction(FunctionDeclaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // visit parameters
-    for (var p in decl.params) {
-      visitParameter(p, cont);
-    }
-
-    // ensure generic types do not enter
-    cont.removeWhere(
-        (t) => decl.typeParams.map((type) => type.name).contains(t));
-
-    // visit return type
-    visitType(decl.returnType, cont);
-
-    return cont;
-  }
-
-  Set<String> visitParameter(Parameter decl, [Set<String>? context]) {
-    final cont = context ??= {};
+import '../../ast/_core/interfaces/compound_declaration.dart';
+import '../../ast/_core/interfaces/declaration.dart';
+import '../../ast/declarations/globals/globals.dart';
+import '../../ast/visitor.dart';
 
-    // just visit type of parameter
-    visitType(decl.type, cont);
+class DependencyVisitation extends Visitation {
+  Set<Declaration> topLevelDeclarations = {};
 
-    return cont;
+  @override
+  void visitGlobalFunctionDeclaration(GlobalFunctionDeclaration node) {
+    node.visitChildren(visitor);
+    topLevelDeclarations.add(node);
   }
 
-  Set<String> visitVariable(VariableDeclaration decl, [Set<String>? context]) {
-    final cont = context ??= {};
-
-    // just return property type
-    visitType(decl.type, cont);
-
-    return cont;
+  @override
+  void visitGlobalVariableDeclaration(GlobalVariableDeclaration node) {
+    node.visitChildren(visitor);
+    topLevelDeclarations.add(node);
   }
 
-  Set<String> visitType(ReferredType type, [Set<String>? context]) {
-    final cont = context ??= {};
+  @override
+  void visitCompoundDeclaration(CompoundDeclaration node) {
+    node.visitChildren(visitor);
 
-    // we need to confirm the types located
-    // check what kind of type [type] is
-    switch (type) {
-      case DeclaredType():
-        cont.add(type.id);
-        break;
-      case GenericType():
-        // do nothing
-        break;
-      case OptionalType():
-        visitType(type.child, cont);
-    }
-    return cont;
+    // Don't add nested classes etc to the top level declarations.
+    if (node.nestingParent == null) topLevelDeclarations.add(node);
   }
 }
diff --git a/pkgs/swift2objc/lib/src/transformer/transform.dart b/pkgs/swift2objc/lib/src/transformer/transform.dart
index 750d2efcd..409252c52 100644
--- a/pkgs/swift2objc/lib/src/transformer/transform.dart
+++ b/pkgs/swift2objc/lib/src/transformer/transform.dart
@@ -8,6 +8,7 @@ import '../ast/_core/interfaces/nestable_declaration.dart';
 import '../ast/declarations/compounds/class_declaration.dart';
 import '../ast/declarations/compounds/struct_declaration.dart';
 import '../ast/declarations/globals/globals.dart';
+import '../ast/visitor.dart';
 import '_core/dependencies.dart';
 import '_core/unique_namer.dart';
 import 'transformers/transform_compound.dart';
@@ -15,15 +16,8 @@ import 'transformers/transform_globals.dart';
 
 typedef TransformationMap = Map<Declaration, Declaration>;
 
-Set<Declaration> generateDependencies(
-    Iterable<Declaration> decls, Iterable<Declaration> allDecls) {
-  final visitor = DependencyVisitor(allDecls);
-  for (final dec in decls) {
-    visitor.visit(dec);
-  }
-
-  return visitor.visitedDeclarations;
-}
+Set<Declaration> generateDependencies(Iterable<Declaration> decls) =>
+    visit(DependencyVisitation(), decls).topLevelDeclarations;
 
 /// Transforms the given declarations into the desired ObjC wrapped declarations
 List<Declaration> transform(List<Declaration> declarations,
@@ -31,7 +25,7 @@ List<Declaration> transform(List<Declaration> declarations,
   final transformationMap = <Declaration, Declaration>{};
 
   final declarations0 = declarations.where(filter).toSet();
-  declarations0.addAll(generateDependencies(declarations0, declarations));
+  declarations0.addAll(generateDependencies(declarations0));
 
   final globalNamer = UniqueNamer(
     declarations0.map((declaration) => declaration.name),
diff --git a/pkgs/swift2objc/lib/src/transformer/transformers/transform_compound.dart b/pkgs/swift2objc/lib/src/transformer/transformers/transform_compound.dart
index cd06487a0..3e079f0f2 100644
--- a/pkgs/swift2objc/lib/src/transformer/transformers/transform_compound.dart
+++ b/pkgs/swift2objc/lib/src/transformer/transformers/transform_compound.dart
@@ -34,7 +34,7 @@ ClassDeclaration transformCompound(
     id: originalCompound.id.addIdSuffix('wrapper'),
     name: parentNamer.makeUnique('${originalCompound.name}Wrapper'),
     hasObjCAnnotation: true,
-    superClass: BuiltInDeclaration.swiftNSObject.asDeclaredType,
+    superClass: objectType,
     isWrapper: true,
     wrappedInstance: wrappedCompoundInstance,
     wrapperInitializer: _buildWrapperInitializer(wrappedCompoundInstance),
diff --git a/pkgs/swift2objc/lib/src/transformer/transformers/transform_globals.dart b/pkgs/swift2objc/lib/src/transformer/transformers/transform_globals.dart
index 47f08a263..b68843d58 100644
--- a/pkgs/swift2objc/lib/src/transformer/transformers/transform_globals.dart
+++ b/pkgs/swift2objc/lib/src/transformer/transformers/transform_globals.dart
@@ -17,7 +17,7 @@ ClassDeclaration transformGlobals(
     id: 'globals'.addIdSuffix('wrapper'),
     name: globalNamer.makeUnique('GlobalsWrapper'),
     hasObjCAnnotation: true,
-    superClass: BuiltInDeclaration.swiftNSObject.asDeclaredType,
+    superClass: objectType,
     isWrapper: true,
   );
 
diff --git a/pkgs/swift2objc/test/unit/parse_function_info_test.dart b/pkgs/swift2objc/test/unit/parse_function_info_test.dart
index 3d86a1b7b..c14b30e20 100644
--- a/pkgs/swift2objc/test/unit/parse_function_info_test.dart
+++ b/pkgs/swift2objc/test/unit/parse_function_info_test.dart
@@ -14,7 +14,7 @@ import 'package:test/test.dart';
 
 void main() {
   final parsedSymbols = {
-    for (final decl in BuiltInDeclaration.values)
+    for (final decl in builtInDeclarations)
       decl.id: ParsedSymbol(json: Json(null), declaration: decl)
   };
   final emptySymbolgraph = ParsedSymbolgraph(parsedSymbols, {});
diff --git a/pkgs/swift2objc/test/unit/parse_type_test.dart b/pkgs/swift2objc/test/unit/parse_type_test.dart
index 309de86f6..e7524e50e 100644
--- a/pkgs/swift2objc/test/unit/parse_type_test.dart
+++ b/pkgs/swift2objc/test/unit/parse_type_test.dart
@@ -19,7 +19,7 @@ void main() {
   final classBar = ClassDeclaration(id: 'Bar', name: 'Bar');
 
   final testDecls = <Declaration>[
-    ...BuiltInDeclaration.values,
+    ...builtInDeclarations,
     classFoo,
     classBar,
   ];