AVAudioFoundation(2)：音视频播放

NSURL *url = [NSURL URLWithString:@"<#Live stream URL#>];
// You may find a test stream at <http://devimages.apple.com/iphone/samples/bipbop/bipbopall.m3u8>.
self.playerItem = [AVPlayerItem playerItemWithURL:url];
[playerItem addObserver:self forKeyPath:@"status" options:0 context:&ItemStatusContext];
self.player = [AVPlayer playerWithPlayerItem:playerItem];

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

player.rate = 0.5;
player.rate = 2.0;

CMTime fiveSecondsIn = CMTimeMake(5, 1);
[player seekToTime:fiveSecondsIn];

CMTime fiveSecondsIn = CMTimeMake(5, 1);
[player seekToTime:fiveSecondsIn toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];

// Register with the notification center after creating the player item.
[[NSNotificationCenter defaultCenter] 
	addObserver:self 
	   selector:@selector(playerItemDidReachEnd:)
    	   name:AVPlayerItemDidPlayToEndTimeNotification
         object:<#The player item#>];
 
- (void)playerItemDidReachEnd:(NSNotification *)notification {
    [player seekToTime:kCMTimeZero];
}

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];
}

- (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;
}

// 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);
}];

#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

@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];
}

static const NSString *ItemStatusContext;

- (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.
        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]);
            }
        });
    }];
}

- (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:sender {
    [self.player play];
}


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