Don't fade in/out embedded if there was no height change

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/Embedded/EmbeddedPaymentElement.swift

@@ -220,7 +220,7 @@ public final class EmbeddedPaymentElement {
 
         self.analyticsHelper = analyticsHelper
         analyticsHelper.logInitialized()
-        self.containerView.updateSuperviewHeight = { [weak self] in
+        self.containerView.needsUpdateSuperviewHeight = { [weak self] in
             guard let self else { return }
             self.delegate?.embeddedPaymentElementDidUpdateHeight(embeddedPaymentElement: self)
         }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/Embedded/EmbeddedPaymentElementContainerView.swift

@@ -8,14 +8,14 @@ import UIKit
 
 /// The view that's vended to the merchant, containing the embedded view.  We use this to be able to swap out the embedded view with an animation when `update` is called.
 class EmbeddedPaymentElementContainerView: UIView {
-    var updateSuperviewHeight: () -> Void = {}
-    private var view: EmbeddedPaymentMethodsView
+    var needsUpdateSuperviewHeight: () -> Void = {}
+    private var contentView: EmbeddedPaymentMethodsView
     private var bottomAnchorConstraint: NSLayoutConstraint!
 
     init(embeddedPaymentMethodsView: EmbeddedPaymentMethodsView) {
-        self.view = embeddedPaymentMethodsView
+        self.contentView = embeddedPaymentMethodsView
         super.init(frame: .zero)
-        addInitialView(view)
+        addInitialView(contentView)
     }
 
     required init?(coder: NSCoder) {
@@ -37,42 +37,52 @@ class EmbeddedPaymentElementContainerView: UIView {
     func updateEmbeddedPaymentMethodsView(_ embeddedPaymentMethodsView: EmbeddedPaymentMethodsView) {
         guard frame.size != .zero else {
             // A zero frame means we haven't been laid out yet. Simply replace the old view to avoid laying out before the view is ready and breaking constraints.
-            self.view.removeFromSuperview()
-            self.view = embeddedPaymentMethodsView
+            contentView.removeFromSuperview()
+            contentView = embeddedPaymentMethodsView
             addInitialView(embeddedPaymentMethodsView)
             return
         }
-        let oldView = view
-        let oldViewHeight = frame.height
-        // Add the new view w/ 0 alpha
+        let oldContentView = contentView
+
+        // Add the new view
         embeddedPaymentMethodsView.translatesAutoresizingMaskIntoConstraints = false
         addSubview(embeddedPaymentMethodsView)
-        view = embeddedPaymentMethodsView
-        embeddedPaymentMethodsView.alpha = 0
+        contentView = embeddedPaymentMethodsView
         NSLayoutConstraint.activate([
             embeddedPaymentMethodsView.topAnchor.constraint(equalTo: layoutMarginsGuide.topAnchor),
             embeddedPaymentMethodsView.leadingAnchor.constraint(equalTo: layoutMarginsGuide.leadingAnchor),
             embeddedPaymentMethodsView.trailingAnchor.constraint(equalTo: layoutMarginsGuide.trailingAnchor),
             // Omit the bottom anchor so that the height is still fixed to the old view height
         ])
-        // important that the view is already laid out before the animation block so that it doesn't animate from zero size.
+
+        // Lay the new view out before the animation block so that it doesn't animate from zero size.
         layoutIfNeeded()
 
+        // Calculate heights of old and new content views to determine if height will change
+        let oldContentViewHeight = oldContentView.frame.size.height
+        let newContentViewHeight = embeddedPaymentMethodsView.frame.size.height
+        let heightWillChange = oldContentViewHeight != newContentViewHeight
+
+        // Fade the old view out and the new view in if the height will change
+        if heightWillChange {
+            embeddedPaymentMethodsView.alpha = 0
+        }
         UIView.animate(withDuration: 0.2) {
             // Re-pin bottom anchor to the new view, thus updating our height
             self.bottomAnchorConstraint.isActive = false
             self.bottomAnchorConstraint = embeddedPaymentMethodsView.bottomAnchor.constraint(equalTo: self.layoutMarginsGuide.bottomAnchor)
             self.bottomAnchorConstraint.isActive = true
             self.layoutIfNeeded()
-            // Fade old view out and new view in
-            oldView.alpha = 0
-            embeddedPaymentMethodsView.alpha = 1
-            if oldViewHeight != self.systemLayoutSizeFitting(.zero).height {
-                // Invoke EmbeddedPaymentElement delegate method so that height does not jump
-                self.updateSuperviewHeight()
+            if heightWillChange {
+                oldContentView.alpha = 0
+                embeddedPaymentMethodsView.alpha = 1
+            }
+            if heightWillChange {
+                // Invoke EmbeddedPaymentElement delegate method so that height of our superview does not jump
+                self.needsUpdateSuperviewHeight()
             }
         } completion: { _ in
-            oldView.removeFromSuperview()
+            oldContentView.removeFromSuperview()
         }
     }
 }