iOS Swift Conversion (#2527)

Converts iOS implementation from Objective-c to Swift

# During the conversion process some updates to the code structure were also made
- Modularize codebase from single file to smaller focused files
- Untangled large nested IF statements
- Added more null checks, since Swift is more strict with null pointers
- Added property to allow for decoding of local video sources with self contained key for offline playback
- Updates example apps to test react-native 0.63.4 and uses auto native dependency imports for android and ios

ios/Video/Features/RCTPictureInPicture.swift

@@ -0,0 +1,75 @@
+import AVFoundation
+import AVKit
+import MediaAccessibility
+import React
+import Foundation
+
+#if TARGET_OS_IOS
+class RCTPictureInPicture: NSObject, AVPictureInPictureControllerDelegate {
+    private var _onPictureInPictureStatusChanged: RCTDirectEventBlock?
+    private var _onRestoreUserInterfaceForPictureInPictureStop: RCTDirectEventBlock?
+    private var _restoreUserInterfaceForPIPStopCompletionHandler:((Bool) -> Void)? = nil
+    private var _pipController:AVPictureInPictureController?
+    private var _isActive:Bool = false
+    
+    init(_ onPictureInPictureStatusChanged: @escaping RCTDirectEventBlock, _ onRestoreUserInterfaceForPictureInPictureStop: @escaping RCTDirectEventBlock) {
+        _onPictureInPictureStatusChanged = onPictureInPictureStatusChanged
+        _onRestoreUserInterfaceForPictureInPictureStop = onRestoreUserInterfaceForPictureInPictureStop
+    }
+    
+    func pictureInPictureControllerDidStartPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
+        guard let _onPictureInPictureStatusChanged = _onPictureInPictureStatusChanged else { return }
+        
+        _onPictureInPictureStatusChanged([ "isActive": NSNumber(value: true)])
+    }
+    
+    func pictureInPictureControllerDidStopPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
+        guard let _onPictureInPictureStatusChanged = _onPictureInPictureStatusChanged else { return }
+        
+        _onPictureInPictureStatusChanged([ "isActive": NSNumber(value: false)])
+    }
+    
+    func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController, restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void) {
+        
+        assert(_restoreUserInterfaceForPIPStopCompletionHandler == nil, "restoreUserInterfaceForPIPStopCompletionHandler was not called after picture in picture was exited.")
+        
+        guard let _onRestoreUserInterfaceForPictureInPictureStop = _onRestoreUserInterfaceForPictureInPictureStop else { return }
+        
+        _onRestoreUserInterfaceForPictureInPictureStop([:])
+        
+        _restoreUserInterfaceForPIPStopCompletionHandler = completionHandler
+    }
+    
+    func setRestoreUserInterfaceForPIPStopCompletionHandler(_ restore:Bool) {
+        guard let _restoreUserInterfaceForPIPStopCompletionHandler = _restoreUserInterfaceForPIPStopCompletionHandler else { return }
+        _restoreUserInterfaceForPIPStopCompletionHandler(restore)
+        self._restoreUserInterfaceForPIPStopCompletionHandler = nil
+    }
+    
+    func setupPipController(_ playerLayer: AVPlayerLayer?) {
+        guard playerLayer != nil && AVPictureInPictureController.isPictureInPictureSupported() && _isActive else { return }
+        // Create new controller passing reference to the AVPlayerLayer
+        _pipController = AVPictureInPictureController(playerLayer:playerLayer!)
+        _pipController?.delegate = self
+    }
+    
+    func setPictureInPicture(_ isActive:Bool) {
+        if _isActive == isActive {
+            return
+        }
+        _isActive = isActive
+        
+        guard let _pipController = _pipController else { return }
+        
+        if _isActive && !_pipController.isPictureInPictureActive {
+            DispatchQueue.main.async(execute: {
+                _pipController.startPictureInPicture()
+            })
+        } else if !_isActive && _pipController.isPictureInPictureActive {
+            DispatchQueue.main.async(execute: {
+                _pipController.stopPictureInPicture()
+            })
+        }
+    }
+}
+#endif