title: PiP AVPlayerViewController issue iPhone
body: <p>I'm studying AVFoundation and I want to create a thing similar to Whatsapp when see a youtube video for example that plays it in PiP mode.
  For this reason I create viewcontroller like this:</p>
  
  <pre><code>#import "ViewController.h"
  #import &lt;AVFoundation/AVFoundation.h&gt;
  #import &lt;AVKit/AVKit.h&gt;
  
  @interface ViewController () &lt;AVPictureInPictureControllerDelegate&gt;
  
  @property (strong, nonatomic) AVPlayerViewController *playerViewController;
  
  @end
  
  @implementation ViewController
  
  - (void)viewDidLoad {
      [super viewDidLoad];
      // Do any additional setup after loading the view, typically from a nib.
  
      NSURL *url = [[NSURL alloc] initWithString:@"https://www.rmp-streaming.com/media/bbb-360p.mp4"];
  
      AVPlayerItem* playerItem = [AVPlayerItem playerItemWithURL:url];
  
      AVPlayer* playVideo = [[AVPlayer alloc] initWithPlayerItem:playerItem];
      self.playerViewController = [[AVPlayerViewController alloc] init];
      self.playerViewController.player = playVideo;
      self.playerViewController.player.volume = 0;
      self.playerViewController.view.frame = self.view.bounds;
      [self.view addSubview:self.playerViewController.view];
      self.playerViewController.showsPlaybackControls = YES;
      self.playerViewController.allowsPictureInPicturePlayback = YES;
      self.playerViewController.videoGravity = AVLayerVideoGravityResizeAspect;
      [playVideo play];
  
  }
  
  - (void)didReceiveMemoryWarning {
      [super didReceiveMemoryWarning];
      // Dispose of any resources that can be recreated.
  }
  
  
  @end
  </code></pre>
  
  <p>In the AppDelegate I did this:</p>
  
  <pre><code>NSError *errore = nil;
      AVAudioSession *sessioneAudio = [AVAudioSession sharedInstance];
      [sessioneAudio setActive:YES error:&amp;errore];
      [sessioneAudio setCategory:AVAudioSessionCategoryPlayback error:&amp;errore];
  </code></pre>
  
  <p>And I enabled Audio,AirPlay and Picture in Picture background modes in project's Capabilities.</p>
  
  <p>My problem is this:</p>
  
  <p>If I run app on iPad device I see the PiP button and I can enabled PiP mode.
  If I run app on iPhone device I don't see PiP button, but I don't understand why.</p>