[ios, macos] Fully documented predicate property

platform/darwin/src/MGLVectorStyleLayer.h

@@ -24,10 +24,101 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, nullable) NSString *sourceLayerIdentifier;
 
 /**
- A predicate that corresponds to the layer's <a href='https://www.mapbox.com/mapbox-gl-style-spec/#types-filter'>filter</a>.
+ The style layer’s predicate.
  
- The predicate's left expression must be a string that identifies a feature
- property, or one of the special keys.
+ Use the style layer’s predicate to include only the features in the source
+ layer that satisfy a condition that you define. If the style layer initially
+ comes from the style, its predicate corresponds to the
+ <a href="https://www.mapbox.com/mapbox-gl-style-spec/#layer-filter">`filter`</a>
+ property in the style JSON.
+ 
+ The following comparison operators are supported.
+ 
+ <ul>
+ <li><code>NSEqualToPredicateOperatorType</code> (<code>=</code>, <code>==</code>)</li>
+ <li><code>NSGreaterThanOrEqualToPredicateOperatorType</code> (<code>>=</code>, <code>=></code>)</li>
+ <li><code>NSLessThanOrEqualToPredicateOperatorType</code> (<code><=</code>, <code>=<</code>)</li>
+ <li><code>NSGreaterThanPredicateOperatorType</code> (<code>></code>)</li>
+ <li><code>NSLessThanPredicateOperatorType</code> (<code><</code>)</li>
+ <li><code>NSNotEqualToPredicateOperatorType</code> (<code>!=</code>, <code><></code>)</li>
+ <li><code>NSBetweenPredicateOperatorType</code> (<code>BETWEEN</code>)</li>
+ </ul>
+ 
+ The following compound operators are supported:
+ 
+ <ul>
+ <li><code>NSAndPredicateType</code> (<code>AND</code>, <code>&&</code>)</li>
+ <li><code>NSOrPredicateType</code> (<code>OR</code>, <code>||</code>)</li>
+ <li><code>NSNotPredicateType</code> (<code>NOT</code>, <code>!</code>)</li>
+ </ul>
+ 
+ The following aggregate operator is supported:
+ 
+ <ul>
+ <li><code>NSInPredicateOperatorType</code> (<code>IN</code>)</li>
+ </ul>
+ 
+ To test whether a feature has or lacks a specific attribute, compare the attribute to `NULL` or `NIL`. Predicates created using the `+[NSPredicate predicateWithValue:]` method are also supported. String operators and custom operators are not supported.
+ 
+ For details about the predicate format string syntax, consult the “Predicate
+ Format String Syntax” chapter of the “Predicate Programming Guide” in Apple
+ developer documentation.
+ 
+ The predicate's left-hand expression must be a string that identifies a feature
+ attribute or, alternatively, one of the following special attributes:
+ 
+ <table>
+ <thead>
+ <tr><th>Attribute</th><th>Meaning</th></tr>
+ </thead>
+ <tbody>
+ <tr>
+    <td><code>$id</code></td>
+    <td>
+        A value that uniquely identifies the feature in the containing source.
+        For details on the types of values that may be associated with this key,
+        consult the documentation for the <code>MGLFeature</code> protocol’s
+        <code>identifier</code> property.
+    </td>
+ </tr>
+ <tr>
+    <td><code>$type</code></td>
+    <td>
+        The type of geometry represented by the feature. A feature’s type is
+        guaranteed to be one of the following strings:
+        <ul>
+            <li>
+                <code>Point</code> for point features, corresponding to the
+                <code>MGLPointAnnotation</code> class
+            </li>
+            <li>
+                <code>LineString</code> for polyline features, corresponding to
+                the <code>MGLPolyline</code> class
+            </li>
+            <li>
+                <code>Polygon</code> for polygon features, corresponding to the
+                <code>MGLPolygon</code> class
+            </li>
+        </ul>
+    </td>
+ </tr>
+ <tr>
+    <td><code>point_count</code></td>
+    <td>The number of point features in a given cluster.</td>
+ </tr>
+ </tbody>
+ </table>
+ 
+ The predicate’s right-hand expression must be an `NSString` (to match strings)
+ or `NSNumber` (to match numbers, including Boolean values) or an array of
+ `NSString`s or `NSNumber`s, depending on the operator and the type of values
+ expected for the attribute being tested. For floating-point values, use
+ `-[NSNumber numberWithDouble:]` instead of `-[NSNumber numberWithFloat:]`
+ to avoid precision issues.
+ 
+ Automatic type casting is not performed. Therefore, a feature only matches this
+ predicate if its value for the attribute in question is of the same type as the
+ value specified in the predicate.
  */
 @property (nonatomic, nullable) NSPredicate *predicate;