3. Actually introduce

3-1. Prerequisites

There are AVPlayerView, AVPlayerViewController, and AVPlayerLayer to implement the player. However, this time we will describe the implementation using AVPlayerLayer.

3-2. Corresponding items for introduction

3-2-1. Check if picture-in-picture is supported

Check it because it may not be supported by the OS such as iOS12.

3-2-2. Start preparing for playback of picture-in-picture

Inform the OS that the picture-in-picture will be played and prepare.

3-2-3. Wait until the picture-in-picture becomes playable

Wait for the OS to be ready for picture-in-picture playback.

3-2-4. Start playing picture-in-picture

The start command is executed only when starting with the picture-in-picture button.

3-3. View sample app

https://developer.apple.com/documentation/avkit/adopting_picture_in_picture_in_a_custom_player

SamplePlayer.swift

func setupPictureInPicture() {
    // Ensure PiP is supported by current device.
    if AVPictureInPictureController.isPictureInPictureSupported() {
        // Create a new controller, passing the reference to the AVPlayerLayer.
        pictureInPictureController = AVPictureInPictureController(playerLayer: playerLayer)
        pictureInPictureController.delegate = self
        
        pipPossibleObservation = pictureInPictureController.observe(\AVPictureInPictureController.isPictureInPicturePossible,
                                                                    options: [.initial, .new]) { [weak self] _, change in
            // Update the PiP button's enabled state.
            self?.pictureInPictureButton.isEnabled = change.newValue ?? false
        }
    } else {
        // PiP isn't supported by the current device. Disable the PiP button.
        pictureInPictureButton.isEnabled = false
    }
}

@IBAction func togglePictureInPictureMode(_ sender: UIButton) {
    if pictureInPictureController.isPictureInPictureActive {
        pictureInPictureController.stopPictureInPicture()
    } else {
        pictureInPictureController.startPictureInPicture()
    }
}

AVPictureInPictureController.isPictureInPictureSupported() Corresponds to 3-2-1. Here, it is determined whether the target device supports picture-in-picture.

AVPictureInPictureController(playerLayer: playerLayer) Corresponds to 3-2-2. I am creating an AVPictureInPictureController. By creating this AVPictureInPictureController, it will be automatically pressed when the home button is pressed. Picture-in-picture playback will begin.

AVPictureInPictureController.isPictureInPicturePossible Corresponds to 3-2-3. There is a several seconds delay </ b> between the generation of AVPictureInPictureController and its activation. Since it changes dynamically, it seems that the sample application uses observe. If you are using Rx, I think it is possible to monitor the parameters with Rx.