fix: conflict when using fullScreenModal presentation in native-sta…

…ck (#272)

## 📜 Description

Fixed a conflict when using `fullScreenModal` presentation in
`native-stack`.

## 💡 Motivation and Context

`willMove(toWindow)` (with `newWindow == nil`) will be called in two
cases:
- view is unmounted;
- a navigation to modal window has occurred.

And we don't need to cleanup a listener if navigation has occurred. So
in this PR I'm switching to `willMove(toSuperview)` method that called
only when view is destroyed (when navigation occurs nothing happens).

Also I decided to unify initialization mechanism between architectures.
The view creation steps are following:
- init
- prop setters
- willMove(toSuperview)

On paper I did an initialization and mounting in `willMove` method
(setter was called on non initialized object). On fabric I initialized
in init method and mounted in prop setters (I didn't use lifecycle
methods in Fabric). However I think that ignoring lifecycle method and
keeping subscriptions is not a good idea (though events are not
propagated and there is no crashes) - potentially we may have bad memory
and other unpleasant exceptions.

So in this PR I decided to unify approach and now we're using next
schema:
- initialize observers in `init`;
- mount/unmount in prop setter;
- mount/unmount in lifecycle.

With such approach potentially on initial mount we can initialize
observer 2 times. To avoid that I've added `isMounted` property to
observers. So now they can be initialized only once (even if you call
`.mount` several times).

Last but not least - I've added private methods mount/unmount on view
level to reduce code duplication (now we have two observers, so one
method initialize both of them).

Closes
#271

## 📢 Changelog

### iOS
- switched from `willMove(toWindow)` to `willMove(toSuperview)`;

## 🤔 How Has This Been Tested?

Tested on iPhone 15 Pro (iOS 17.0.1).

## 📝 Checklist

- [x] CI successfully passed

ios/observers/FocusedInputLayoutObserver.swift

@@ -25,6 +25,8 @@ let noFocusedInputEvent: [String: Any] = [
 public class FocusedInputLayoutObserver: NSObject {
   // class members
   var onEvent: (NSDictionary) -> Void
+  // state variables
+  private var isMounted = false
   // input tracking
   private var currentInput: UIView?
   private var hasKVObserver = false
@@ -37,6 +39,12 @@ public class FocusedInputLayoutObserver: NSObject {
   }
 
   @objc public func mount() {
+    if isMounted {
+      return
+    }
+
+    isMounted = true
+
     NotificationCenter.default.addObserver(
       self,
       selector: #selector(keyboardWillShow),
@@ -52,6 +60,7 @@ public class FocusedInputLayoutObserver: NSObject {
   }
 
   @objc public func unmount() {
+    isMounted = false
     // swiftlint:disable:next notification_center_detachment
     NotificationCenter.default.removeObserver(self)
   }

ios/observers/KeyboardMovementObserver.swift

@@ -31,6 +31,7 @@ public class KeyboardMovementObserver: NSObject {
   private var prevKeyboardPosition = 0.0
   private var displayLink: CADisplayLink?
   private var hasKVObserver = false
+  private var isMounted = false
   // state variables
   private var keyboardHeight: CGFloat = 0.0
   private var duration = 0
@@ -45,6 +46,12 @@ public class KeyboardMovementObserver: NSObject {
   }
 
   @objc public func mount() {
+    if isMounted {
+      return
+    }
+
+    isMounted = true
+
     NotificationCenter.default.addObserver(
       self,
       selector: #selector(keyboardWillDisappear),
@@ -138,6 +145,7 @@ public class KeyboardMovementObserver: NSObject {
   }
 
   @objc public func unmount() {
+    isMounted = false
     // swiftlint:disable:next notification_center_detachment
     NotificationCenter.default.removeObserver(self)
   }

ios/views/KeyboardControllerView.mm

@@ -156,17 +156,36 @@ - (void)updateProps:(Props::Shared const &)props oldProps:(Props::Shared const &
 
   if (newViewProps.enabled != oldViewProps.enabled) {
     if (newViewProps.enabled) {
-      [inputObserver mount];
-      [keyboardObserver mount];
+      [self mount];
     } else {
-      [inputObserver unmount];
-      [keyboardObserver unmount];
+      [self unmount];
     }
   }
 
   [super updateProps:props oldProps:oldProps];
 }
 
+- (void)willMoveToSuperview:(UIView *)newSuperview
+{
+  if (newSuperview == nil) {
+    [self unmount];
+  } else {
+    [self mount];
+  }
+}
+
+- (void)mount
+{
+  [inputObserver mount];
+  [keyboardObserver mount];
+}
+
+- (void)unmount
+{
+  [inputObserver unmount];
+  [keyboardObserver unmount];
+}
+
 Class<RCTComponentViewProtocol> KeyboardControllerViewCls(void)
 {
   return KeyboardControllerView.class;

ios/views/KeyboardControllerViewManager.swift

@@ -24,11 +24,9 @@ class KeyboardControllerView: UIView {
   @objc var enabled: ObjCBool = true {
     didSet {
       if enabled.boolValue {
-        inputObserver?.mount()
-        keyboardObserver?.mount()
+        mount()
       } else {
-        inputObserver?.unmount()
-        keyboardObserver?.unmount()
+        unmount()
       }
     }
   }
@@ -37,28 +35,26 @@ class KeyboardControllerView: UIView {
     self.bridge = bridge
     eventDispatcher = bridge.eventDispatcher()
     super.init(frame: frame)
+    inputObserver = FocusedInputLayoutObserver(handler: onInput)
+    keyboardObserver = KeyboardMovementObserver(handler: onEvent, onNotify: onNotify)
   }
 
   @available(*, unavailable)
   required init?(coder _: NSCoder) {
     fatalError("init(coder:) has not been implemented")
   }
 
-  override func willMove(toWindow newWindow: UIWindow?) {
-    if newWindow == nil {
-      // Will be removed from a window
-      inputObserver?.unmount()
-      keyboardObserver?.unmount()
-    }
-  }
+  // for mounting/unmounting observers for lifecycle events we're using willMove(toSuperview) method
+  // not willMove(toWindow)
+  // see https://github.com/kirillzyusko/react-native-keyboard-controller/issues/271
+  override func willMove(toSuperview newSuperview: UIView?) {
+    super.willMove(toSuperview: newSuperview)
 
-  override func didMoveToWindow() {
-    if window != nil {
-      // Added to a window
-      inputObserver = FocusedInputLayoutObserver(handler: onInput)
-      inputObserver?.mount()
-      keyboardObserver = KeyboardMovementObserver(handler: onEvent, onNotify: onNotify)
-      keyboardObserver?.mount()
+    if newSuperview == nil {
+      // The view is about to be removed from its superview (destroyed)
+      unmount()
+    } else {
+      mount()
     }
   }
 
@@ -90,4 +86,14 @@ class KeyboardControllerView: UIView {
   func onNotify(event: String, data: Any) {
     KeyboardController.shared()?.sendEvent(event, body: data)
   }
+
+  private func mount() {
+    inputObserver?.mount()
+    keyboardObserver?.mount()
+  }
+
+  private func unmount() {
+    inputObserver?.unmount()
+    keyboardObserver?.unmount()
+  }
 }