NSArray *items = <#An array of player items#>;
AVQueuePlayer *queuePlayer = [[AVQueuePlayer alloc] initWithItems:items];

AVPlayerItem *anItem = <#Get a player item#>;
if ([queuePlayer canInsertItem:anItem afterItem:nil]) {
    [queuePlayer insertItem:anItem afterItem:nil];
}

Monitoring Playback

Responding to a Change in Status

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object
change:(NSDictionary *)change context:(void *)context {
    
    if (context == <#Player status context#>) {
        AVPlayer *thePlayer = (AVPlayer *)object;
        if ([thePlayer status] == AVPlayerStatusFailed) {
            NSError *error = [<#The AVPlayer object#> error];
            // Respond to error: for example, display an alert sheet.
            return;
        }
        // Deal with other status change if appropriate.
    }
    // Deal with other change notifications if appropriate.
    [super observeValueForKeyPath:keyPath ofObject:object
        change:change context:context];
    return;
}

Tracking Readiness for Visual Display

Tracking Time

// Assume a property: @property (strong) id playerObserver;

Float64 durationSeconds = CMTimeGetSeconds([<#An asset#> duration]);
CMTime firstThird = CMTimeMakeWithSeconds(durationSeconds/3.0, 1);
CMTime secondThird = CMTimeMakeWithSeconds(durationSeconds*2.0/3.0, 1);
NSArray *times = @[[NSValue valueWithCMTime:firstThird], [NSValue valueWithCMTime:secondThird]];

self.playerObserver = [<#A player#> addBoundaryTimeObserverForTimes:times queue:NULL usingBlock:^{

NSString *timeDescription = (NSString *)
CFBridgingRelease(CMTimeCopyDescription(NULL, [self.player currentTime]));
NSLog(@"Passed a boundary at %@", timeDescription);
}];

Reaching the End of an Item

[[NSNotificationCenter defaultCenter] addObserver:<#The observer, typically self#>
    selector:@selector(<#The selector name#>)
    name:AVPlayerItemDidPlayToEndTimeNotification
    object:<#A player item#>];

Putting It All Together: Playing a Video File Using AVPlayerLayer

The Player View 

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface PlayerView : UIView
@property (nonatomic) AVPlayer *player;
@end

@implementation PlayerView
+ (Class)layerClass {
    return [AVPlayerLayer class];
}
- (AVPlayer*)player {
        return [(AVPlayerLayer *)[self layer] player];
}
- (void)setPlayer:(AVPlayer *)player {
        [(AVPlayerLayer *)[self layer] setPlayer:player];
}
@end

A Simple View Controller

@class PlayerView;
@interface PlayerViewController : UIViewController

@property (nonatomic) AVPlayer *player;
@property (nonatomic) AVPlayerItem *playerItem;
@property (nonatomic, weak) IBOutlet PlayerView *playerView;
@property (nonatomic, weak) IBOutlet UIButton *playButton;
- (IBAction)loadAssetFromFile:sender;
- (IBAction)play:sender;
- (void)syncUI;
@end

- (void)syncUI {
    if ((self.player.currentItem != nil) &&
        ([self.player.currentItem status] == AVPlayerItemStatusReadyToPlay)) {
        self.playButton.enabled = YES;
    }
    else {
        self.playButton.enabled = NO;
    }
}

- (void)viewDidLoad {
    [super viewDidLoad];
    [self syncUI];
}

- (IBAction)loadAssetFromFile:sender {
    
    NSURL *fileURL = [[NSBundle mainBundle]
        URLForResource:<#@"VideoFileName"#> withExtension:<#@"extension"#>];
    
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:fileURL options:nil];
    NSString *tracksKey = @"tracks";
    
    [asset loadValuesAsynchronouslyForKeys:@[tracksKey] completionHandler:
    ^{
        // The completion block goes here.
    }];
}

在回调block中，我们可以根据asset创建AVPlayerItem 实例，并且使用该AVPlayerItem 对象初始化AVplay，在为view的player赋值。当我们创建了asset，简单的创建player item并不意味着准备使用，我们需要确定什么时候可以播放，所有观察status属性。我们应该在为player实例赋值player item之前，添加观察者。

// Define this constant for the key-value observation context.
static const NSString *ItemStatusContext;

// Completion handler block.
dispatch_async(dispatch_get_main_queue(),
^{
   NSError *error;
   AVKeyValueStatus status = [asset statusOfValueForKey:tracksKey error:&error];

   if (status == AVKeyValueStatusLoaded) {
       self.playerItem = [AVPlayerItem playerItemWithAsset:asset];
       // ensure that this is done before the playerItem is associated with the player
       [self.playerItem addObserver:self
                        forKeyPath:@"status"
                        options:NSKeyValueObservingOptionInitial
                        context:&ItemStatusContext];
       [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(playerItemDidReachEnd:)
                                             name:AVPlayerItemDidPlayToEndTimeNotification
                                             object:self.playerItem];
        self.player = [AVPlayer playerWithPlayerItem:self.playerItem];
        [self.playerView setPlayer:self.player];
}
else {
        // You should deal with the error appropriately.
        NSLog(@"The asset‘s tracks were not loaded:\n%@", [error localizedDescription]);
  }
});

Responding to the Player Item’s Status Change

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object
change:(NSDictionary *)change context:(void *)context {
    
    if (context == &ItemStatusContext) {
        dispatch_async(dispatch_get_main_queue(),
                       ^{
                        [self syncUI];
            });
        return;
    }
    [super observeValueForKeyPath:keyPath ofObject:object
        change:change context:context];
    return;
}

- (IBAction)play:(UIButton *)sender {
    [player play];
}

// Register with the notification center after creating the player item.
[[NSNotificationCenter defaultCenter] addObserver:self
                       selector:@selector(playerItemDidReachEnd:)
                       name:AVPlayerItemDidPlayToEndTimeNotification
                       object:[self.player currentItem]];

- (void)playerItemDidReachEnd:(NSNotification *)notification {
    [self.player seekToTime:kCMTimeZero];
}