How do I intercept tapping of the done button in A

问题:

I created an AVPlayerViewController and an attached AVPlayer in the viewDidAppear method of a custom UIViewController. However, when I press the "Done" button my custom view controller is dismissed automatically.

I would like to intercept this action in order to use my own unwind Segue, but I'm not sure how to do this. I've found examples for MPMoviePlayerViewController but not AVPlayerViewController.

The code I found for MPMoviePlayerViewController is below:

- (void)playVideo:(NSString *)aVideoUrl {
    // Initialize the movie player view controller with a video URL string
    MPMoviePlayerViewController *playerVC = [[[MPMoviePlayerViewController alloc] initWithContentURL:[NSURL URLWithString:aVideoUrl]] autorelease];

    // Remove the movie player view controller from the "playback did finish" notification observers
    [[NSNotificationCenter defaultCenter] removeObserver:playerVC
                                                name:MPMoviePlayerPlaybackDidFinishNotification
                                              object:playerVC.moviePlayer];

    // Register this class as an observer instead
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(movieFinishedCallback:)
                                                 name:MPMoviePlayerPlaybackDidFinishNotification
                                               object:playerVC.moviePlayer];

    // Set the modal transition style of your choice
    playerVC.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;

    // Present the movie player view controller
    [self presentModalViewController:playerVC animated:YES];

    // Start playback
    [playerVC.moviePlayer prepareToPlay];
    [playerVC.moviePlayer play];
}

- (void)movieFinishedCallback:(NSNotification *)aNotification {
    // Obtain the reason why the movie playback finished
    NSNumber *finishReason = [[aNotification userInfo] objectForKey:MPMoviePlayerPlaybackDidFinishReasonUserInfoKey];

    // Dismiss the view controller ONLY when the reason is not "playback ended"
    if ([finishReason intValue] != MPMovieFinishReasonPlaybackEnded) {
        MPMoviePlayerController *moviePlayer = [aNotification object];

        // Remove this class from the observers
        [[NSNotificationCenter defaultCenter] removeObserver:self
                                                        name:MPMoviePlayerPlaybackDidFinishNotification
                                                      object:moviePlayer];

        // Dismiss the view controller
        [self dismissModalViewControllerAnimated:YES];
    }
}

I asked Apple about this problem and they've replied as follows:

Thank you for contacting Apple Developer Technical Support (DTS). Our engineers have reviewed your request and have concluded that there is no supported way to achieve the desired functionality given the currently shipping system configurations.

回答1:

I subclassed AVPlayerViewController and am posting a notification from viewWillDisappear to indicate dismissing of AVPlayerViewController.

- (void) viewWillDisappear:(BOOL)animated {
    [[NSNotificationCenter defaultCenter] postNotificationName:kPlayerViewDismissedNotification object:nil];
    [super viewWillDisappear:animated];
}

This might not be 100% correct (as it would fail if you have another view being displayed over AVPlayerViewController), but it worked for me as AVPlayerViewController is always at the top of the stack.

回答2:

The fact that Apple provides no built-in way to handle the Done button is disappointing.

I didn't feel like inheriting from AVPlayerViewController, because it isn't supported by Apple and will probably open up a can of worms in one of the next iOS updates.

My workaround is to have a timer fire every 200 msec and check for the following condition:

if (playerVC.player.rate == 0 &&
   (playerVC.isBeingDismissed || playerVC.nextResponder == nil)) {
  // Handle user Done button click and invalidate timer
}

The player's rate property of 0 indicates that the video is no longer playing. And if the view controller is being dismissed or already dismissed, we can safely assume that the user clicked the Done button.

回答3:

You could do it by subclassing AVPLayerViewController. But there is some undefined behaviour due to this. (Given in Apple docs. See below) I also tried subclassing AVPlayerViewController and I faced Memory issue.

According to the Apple Docs:

Do not subclass AVPlayerViewController. Overriding this class’s methods is unsupported and results in undefined behavior.

Currently, they do not offer a callback when the AVPlayerViewController is dismissed. See Apple developer forum:

• Thread1
• Thread2

In thread1 Apple guy says:

I still believe that managing the exit of the AVPlayerViewController instance manually by utilizing the recommended gesture method above would be the most reliable way to know that the player view controller has been dismissed, since you'll be in charge of its dismissal at that point

Hope it helps!

---

Well, there is a fix to the problem. You can add a button as a subview of AVPlayerViewController. By doing so, you could intercept done button tap gesture.

回答4:

I solved by keeping a weak reference to the AVPlayerViewController instance, and monitoring with a timer where the reference change to nil.

private weak var _playerViewController : AVPlayerViewController? // global reference
    ...
    ...
    let playerController = AVPlayerViewController() // local reference
    ...
    self.present(playerController, animated: true) { [weak self] in
        playerController.player?.play()
        self?._playerViewController = playerController
        // schedule a timer to intercept player dismissal
        Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { [weak self] (timer) in
        if self?.playerViewController == nil {
            // player vc dismissed
            timer.invalidate()
        }
}

回答5:

Since there don't seem to be any perfect answers here, a workaround you can use for some situations is to monitor whether the AVPlayer is still playing and set an observer in case it closes automatically after being played all the way through.

  var player:AVPlayer = AVPlayer()
  var videoPlayTimer:NSTimer = NSTimer()

  func playVideo(action: UIAlertAction)  -> Void {

    player = AVPlayer(URL: NSURL(fileURLWithPath: myFilePath))
    player.actionAtItemEnd = .None

    let playerController = AVPlayerViewController()
    playerController.player = player
    self.presentViewController(playerController, animated: true) {      
      self.player.play()
      self.monitorVideoPlayStatus()
      NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(MyViewController.onVideoEnd(_:)), name: AVPlayerItemDidPlayToEndTimeNotification, object: self.player.currentItem)
    }
  }

  //setting a timer to monitor video play status in case it is closed by user
  func monitorVideoPlayStatus(){
    if ((player.rate != 0) && (player.error == nil)) {
      NSLog("player is playing")
      videoPlayTimer = NSTimer.after(0.5, monitorVideoPlayStatus)
    } else {
      NSLog("player is NOT playing")
      onVideoEnd()
    }
  }

  //will be called when video plays all the way through
  func onVideoEnd(note: NSNotification){
    NSLog("onVideoEnd")
    onVideoEnd()

    //canceling video play monitor
    videoPlayTimer.invalidate()
  }

  func onVideoEnd(){
    NSLog("finished playing video")
    NSNotificationCenter.defaultCenter().removeObserver(self, name: AVPlayerItemDidPlayToEndTimeNotification, object: nil)

    //*******
    //DO WHATEVER YOU WANT AFTER VIDEO HAS ENDED RIGHT HERE
    //*******
  }

回答6:

Here is code how I managed to detect clicks.

In application delegate class. But it detects every buttons find in that view. You can add some control, check title something like that.

-(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window{
    if ([window.rootViewController isKindOfClass:[AVPlayerViewController class]]) {
        return UIInterfaceOrientationMaskAll;
    }
    else if(window.rootViewController.presentedViewController != nil)
    {
        if ([window.rootViewController.presentedViewController isKindOfClass:[AVPlayerViewController class]] || [window.rootViewController.presentedViewController isKindOfClass:NSClassFromString(@"AVFullScreenViewController")]) {
            if ([window.rootViewController.presentedViewController isKindOfClass:NSClassFromString(@"AVFullScreenViewController")]) {
                [self findAllButton:window.rootViewController.presentedViewController.view];
            }
            return UIInterfaceOrientationMaskAll;
        }
    }
    [[UIDevice currentDevice] setValue:@(UIInterfaceOrientationPortrait) forKey:@"orientation"];
    [[UIApplication sharedApplication] setStatusBarHidden:NO];
    return UIInterfaceOrientationMaskPortrait;
}

-(void)findAllButton:(UIView*)view{
    for (UIView *subV in view.subviews) {
        if ([subV isKindOfClass:[UIButton class]]) {
            NSLog(@"%@",[((UIButton*)subV) titleForState:UIControlStateNormal]);
            [((UIButton*)subV) addTarget:self action:@selector(doneButtonCliked) forControlEvents:UIControlEventTouchUpInside];
        }
        else{
            [self findAllButton:subV];
        }
    }
}
-(IBAction)doneButtonCliked{
    NSLog(@"DONECLICK");
}

回答7:

If you have a view controller A that presents a AVPlayerViewController, you could probably check in viewDidAppear/viewWillAppear inside VC A. Whenever those are called, at least we would know that the AVPlayerViewController is no longer shown and thus should not be playing.

回答8:

One way is to add additional action to the existing "Done" button on the AVPlayerViewController by searching the respective UIButton inside the subviews of AVPlayerViewController. Once the button is found, add a custom action using addTarget:action:forControlEvents:

At least this works for me.

- (UIButton*)findButtonOnView:(UIView*)view withText:(NSString*)text
{
    __block UIButton *retButton = nil;

    [view.subviews enumerateObjectsUsingBlock:^(__kindof UIView * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        if([obj isKindOfClass:[UIButton class]]) {
            UIButton *button = (UIButton*)obj;
            if([button.titleLabel.text isEqualToString:text]) {
                retButton = button;
                *stop = YES;
            }
        }
        else if([obj isKindOfClass:[UIView class]]) {
            retButton = [self findButtonOnView:obj withText:text];

            if(retButton) {
                *stop = YES;
            }
        }
    }];

    return retButton;
}

- (void)showPlayer:(AVPlayer*)player
{
    AVPlayerViewController *vc = [[AVPlayerViewController alloc] init];
    vc.player = player;

    [self presentViewController:vc animated:NO completion:^{
        UIButton *doneButton = [self findButtonOnView:vc.view withText:@"Done"];
        [doneButton addTarget:self action:@selector(doneAction:) forControlEvents:UIControlEventTouchUpInside];
        [vc.player play];
    }];

}

- (void)doneAction:(UIButton*)button
{
    // perform any action required here
}