Address Element - fix some visual glitches (#1362)

* Fixes checkbox having ambigous layout - this occasionally caused bad layouts when 'Billing address is same as shipping' is toggled after PaymentSheet is dismissed and reappears

* Rewrite animateAlongsideKeyboard to use UIViewPropertyAnimator instead of UIView.animate

* Fix curve

* Update snapshot tests

* Improve transition animation to autocomplete

Stripe/AutoCompleteViewController.swift

@@ -162,6 +162,7 @@ class AutoCompleteViewController: UIViewController {
             return
         }
 
+        view.layoutIfNeeded() // Ensures the view is laid out before animating
         let keyboardViewEndFrame = view.convert(keyboardScreenEndFrame, from: view.window)
         let keyboardInViewHeight = view.safeAreaLayoutGuide.layoutFrame.intersection(keyboardViewEndFrame).height
         if notification.name == UIResponder.keyboardWillHideNotification {

StripeUICore/StripeUICore/Source/Categories/UIView+StripeUICore.swift

@@ -57,19 +57,21 @@ import UIKit
     ) {
         let userInfo = notification.userInfo
 
-        guard let duration = userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? NSNumber else {
+        guard let duration = userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? Double else {
             animations()
             return
         }
 
+        // Get keyboard animation info
         // TODO(ramont): extract animation curve from `keyboardAnimationCurveUserInfoKey`
         // (see: http://www.openradar.me/42609976)
+        let curve = UIView.AnimationCurve.easeOut
 
-        UIView.animate(
-            withDuration: duration.doubleValue,
-            delay: 0,
-            options: [.curveEaseOut],
-            animations: animations
-        )
+        // Animate the container above the keyboard
+        // Note: We prefer UIViewPropertyAnimator over UIView.animate because it handles consecutive animation calls better. Sometimes this happens when one text field resigns and another immediately becomes first responder.
+        let animator = UIViewPropertyAnimator(duration: duration, curve: curve) {
+            animations()
+        }
+        animator.startAnimation()
     }
 }

StripeUICore/StripeUICore/Source/Elements/Checkbox/CheckboxButton.swift

@@ -172,6 +172,8 @@ import UIKit
         addSubview(checkbox)
         addSubview(stackView)
 
+        let minimizeHeight = stackView.heightAnchor.constraint(equalTo: heightAnchor)
+        minimizeHeight.priority = .defaultLow
         NSLayoutConstraint.activate([
             // Checkbox
             checkboxAlignmentConstraint,
@@ -183,7 +185,8 @@ import UIKit
             stackView.topAnchor.constraint(greaterThanOrEqualTo: topAnchor),
             stackView.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor),
             stackView.leadingAnchor.constraint(equalTo: checkbox.trailingAnchor, constant: 6),
-            stackView.trailingAnchor.constraint(equalTo: trailingAnchor)
+            stackView.trailingAnchor.constraint(equalTo: trailingAnchor),
+            minimizeHeight
         ])
     }