播放堆叠视频

Question

我有多个 imageview 子视图根据我的传入数据堆叠在一起。基本上所有这些子视图都根据我的传入数据设置为图像或视频层。我遇到的问题是播放视频。我可以播放堆栈中的第一个视频，但之后的每个视频都只是第一个视频的声音。我怎样才能相应地发挥每一个？

视图是通过像 snapchat 这样的点击事件来导航的。见下文：

@interface SceneImageViewController ()

@property (strong, nonatomic) NSURL *videoUrl;
@property (strong, nonatomic) AVPlayer *avPlayer;
@property (strong, nonatomic) AVPlayerLayer *avPlayerLayer;

@end

@implementation SceneImageViewController

- (void)viewDidLoad {

[super viewDidLoad];

self.mySubviews = [[NSMutableArray alloc] init];
self.videoCounterTags = [[NSMutableArray alloc] init];

int c = (int)[self.scenes count];
c--;
NSLog(@"int c = %d", c);
self.myCounter = [NSNumber numberWithInt:c];


for (int i=0; i<=c; i++) {

    //create imageView
    UIImageView *imageView =[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
    [imageView setUserInteractionEnabled:YES]; // <--- This is very important
    imageView.tag = i;                        // <--- Add tag to track this subview in the view stack
    [self.view addSubview:imageView];
    NSLog(@"added image view %d", i);


    //get scene object
    PFObject *sceneObject = self.scenes[i];


    //get the PFFile and filetype
    PFFile *file = [sceneObject objectForKey:@"file"];
    NSString *fileType = [sceneObject objectForKey:@"fileType"];



    //check the filetype
    if ([fileType  isEqual: @"image"])
    {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
        //get image
        NSURL *imageFileUrl = [[NSURL alloc] initWithString:file.url];
        NSData *imageData = [NSData dataWithContentsOfURL:imageFileUrl];
            dispatch_async(dispatch_get_main_queue(), ^{
        imageView.image = [UIImage imageWithData:imageData];
            });
        });

    }

    //its a video
    else
    {
        // the video player
        NSURL *fileUrl = [NSURL URLWithString:file.url];

        self.avPlayer = [AVPlayer playerWithURL:fileUrl];
        self.avPlayer.actionAtItemEnd = AVPlayerActionAtItemEndNone;

        self.avPlayerLayer = [AVPlayerLayer playerLayerWithPlayer:self.avPlayer];
        //self.avPlayerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(playerItemDidReachEnd:)
                                                     name:AVPlayerItemDidPlayToEndTimeNotification
                                                   object:[self.avPlayer currentItem]];

        CGRect screenRect = [[UIScreen mainScreen] bounds];

        self.avPlayerLayer.frame = CGRectMake(0, 0, screenRect.size.width, screenRect.size.height);
        [imageView.layer addSublayer:self.avPlayerLayer];

        NSNumber *tag = [NSNumber numberWithInt:i+1];

        NSLog(@"tag = %@", tag);

        [self.videoCounterTags addObject:tag];

        //[self.avPlayer play];
    }



}



UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(viewTapped:)];

[self.view bringSubviewToFront:self.screen];

[self.screen addGestureRecognizer:tapGesture];


}


 - (void)viewTapped:(UIGestureRecognizer *)gesture{

NSLog(@"touch!");

[self.avPlayer pause];

int i = [self.myCounter intValue];
NSLog(@"counter = %d", i);



for(UIImageView *subview in [self.view subviews]) {

    if(subview.tag== i) {

        [subview removeFromSuperview];
    }
}

if ([self.videoCounterTags containsObject:self.myCounter]) {
    NSLog(@"play video!!!");
    [self.avPlayer play];
}

if (i == 0) {
    [self.avPlayer pause];
    [self.navigationController popViewControllerAnimated:NO];
}


i--;
self.myCounter = [NSNumber numberWithInt:i];


NSLog(@"counter after = %d", i);





}

Answer 1

看看您设置 myCounter 变量的方式。它被设置一次并且在点击视图之前永远不会改变，然后它被设置为场景计数，-1。

此外，请尝试查看您设置 _avPlayer 指针变量的方式。它总是被一遍又一遍地设置，似乎在 for 循环中你想要存储引用而不是简单地将相同的指针更新为场景集合中最新的值。

此外，来自 Apple 的 documentation：

You can create arbitrary numbers of player layers with the same AVPlayer object. Only the most recently created player layer will actually display the video content on-screen.

因此，有可能因为您使用同一个 AVPlayer 对象来创建所有这些 AVPlayer 层，所以您永远不会看到一个以上的实际视频层工作。

Answer 2

Brooks Hanes 所说的是正确的，您一直在覆盖 avplayer。这是我建议你做的：

将点击手势添加到 imageView 而不是屏幕（或者为了更简洁的方法，请改用 UIButton）：

UIImageView *imageView =[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
[imageView setUserInteractionEnabled:YES]; // <--- This is very important
imageView.tag = i;                        // <--- Add tag to track this subview in the view stack
[self.view addSubview:imageView];
NSLog(@"added image view %d", i);
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:imageView action:@selector(viewTapped:)];
[imageView addGestureRecognizer:tapGesture];

通过这种方式，在您的 viewTapped: 方法中，您可以像这样获取按下图像的标签：gesture.view.tag 而不是使用 myCounter。

要使视频正常运行，您可以为每个视频创建一个新的 AVPlayer，但这可能会占用大量内存。更好的方法是使用 AVPlayerItem 并在更改视频时切换 AVPlayer 的 AVPlayerItem。

所以在 for 循环中做这样的事情 self.videoFiles 是 NSMutableDictionary 属性:

           // the video player
            NSNumber *tag = [NSNumber numberWithInt:i+1];
            NSURL *fileUrl = [NSURL URLWithString:file.url];
          //save your video file url paired with the ImageView it belongs to.
           [self.videosFiles setObject:fileUrl forKey:tag];
// you only need to initialize the player once.
            if(self.avPlayer == nil){
                AVAsset *asset = [AVAsset assetWithURL:fileUrl];
                AVPlayerItem *item = [[AVPlayerItem alloc] initWithAsset:asset];
                self.avPlayer = [[AVPlayer alloc] initWithPlayerItem:item];
                self.avPlayer.actionAtItemEnd = AVPlayerActionAtItemEndNone;
                [[NSNotificationCenter defaultCenter] addObserver:self
                    selector:@selector(playerItemDidReachEnd:)
                name:AVPlayerItemDidPlayToEndTimeNotification
                object:[self.avPlayer currentItem]];
            }
            // you don't need to keep the layer as a property 
            // (unless you need it for some reason 
            AVPlayerLayer* avPlayerLayer = [AVPlayerLayer playerLayerWithPlayer:self.avPlayer];
            avPlayerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

            CGRect screenRect = [[UIScreen mainScreen] bounds];                
            avPlayerLayer.frame = CGRectMake(0, 0, screenRect.size.width, screenRect.size.height);
            [imageView.layer addSublayer:avPlayerLayer];
            NSLog(@"tag = %@", tag);                
            [self.videoCounterTags addObject:tag];

现在在你的 viewTapped:

 if ([self.videoCounterTags containsObject:gesture.view.tag]) { 

  NSLog(@"play video!!!");
    AVAsset *asset = [AVAsset assetWithURL:[self.videoFiles objectForKey:gesture.view.tag]];
    AVPlayerItem *item = [[AVPlayerItem alloc] initWithAsset:asset];
    self.avPlayer replaceCurrentItemWithPlayerItem: item];
    [self.avLayer play];
}

或者改用 self.videoFiles 然后你根本不需要 self.videoCounterTags:

 NSURL* fileURL = [self.videoFiles objectForKey:gesture.view.tag];
 if (fileURL!=nil) {    
     NSLog(@"play video!!!");
     AVAsset *asset = [AVAsset assetWithURL:fileURL];
     AVPlayerItem *item = [[AVPlayerItem alloc] initWithAsset:asset];
     self.avPlayer replaceCurrentItemWithPlayerItem: item];
     [self.avLayer play];
 }

这就是它的要点。

播放堆叠视频

Playing stacked videos

video

objective-c

avfoundation

ios