Add PiP for iOS

Model/Player/PiPDelegate.swift

@@ -0,0 +1,35 @@
+import AVKit
+import Foundation
+
+final class PiPDelegate: NSObject, AVPictureInPictureControllerDelegate {
+    var player: PlayerModel!
+
+    func pictureInPictureController(
+        _: AVPictureInPictureController,
+        failedToStartPictureInPictureWithError error: Error
+    ) {
+        print(error.localizedDescription)
+    }
+
+    func pictureInPictureControllerWillStartPictureInPicture(_: AVPictureInPictureController) {}
+
+    func pictureInPictureControllerDidStartPictureInPicture(_: AVPictureInPictureController) {}
+
+    func pictureInPictureControllerDidStopPictureInPicture(_: AVPictureInPictureController) {
+        if player?.avPlayerBackend.switchToMPVOnPipClose ?? false {
+            DispatchQueue.main.async { [weak player] in
+                player?.avPlayerBackend.switchToMPVOnPipClose = false
+                player?.saveTime { [weak player] in
+                    player?.changeActiveBackend(from: .appleAVPlayer, to: .mpv)
+                }
+            }
+        }
+    }
+
+    func pictureInPictureControllerWillStopPictureInPicture(_: AVPictureInPictureController) {}
+
+    func pictureInPictureController(
+        _: AVPictureInPictureController,
+        restoreUserInterfaceForPictureInPictureStopWithCompletionHandler _: @escaping (Bool) -> Void
+    ) {}
+}