[转]AVPlayer的基本使用

在iOS开发中，播放视频通常有两种方式，一种是使用MPMoviePlayerController（需要导入MediaPlayer.Framework），还有一种是使用AVPlayer。关于这两个类的区别可以参考http://stackoverflow.com/questions/8146942/avplayer-and-mpmovieplayercontroller-differences，简而言之就是MPMoviePlayerController使用更简单，功能不如AVPlayer强大，而AVPlayer使用稍微麻烦点，不过功能更加强大。这篇博客主要介绍下AVPlayer的基本使用，由于博主也是刚刚接触，所以有问题大家直接指出~

　　在开发中，单纯使用AVPlayer类是无法显示视频的，要将视频层添加至AVPlayerLayer中，这样才能将视频显示出来，所以先在ViewController的@interface中添加以下属性

1 2	@property (nonatomic ,strong) AVPlayer *player; @property (nonatomic ,strong) AVPlayerItem *playerItem;<br>@property (nonatomic ,weak) IBOutletPlayerView *playerView;

其中playerView继承自UIView，不过重写了set和get方法，用于将player添加至playerView的AVPlayerLayer中，这样才能顺利将视频显示出来

在PlayerView.h中声明一个AVPlayer对象，由于默认的layer是CALayer，而AVPlayer只能添加至AVPlayerLayer中，所以我们改变一下layerClass，这样PlayerView的默认layer就变了，之后我们可以把在viewController中初始化的AVPlayer对象赋给AVPlayerLayer的player属性。

　PlayerView.h　

　@property (nonatomic ,strong) AVPlayer *player;

 

　PlayerView.m

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

然后在viewDidLoad中执行初始化：

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NSURL *videoUrl = [NSURL URLWithString:@"http://www.jxvdy.com/file/upload/201405/05/18-24-58-42-627.mp4"]; self.playerItem = [AVPlayerItem playerItemWithURL:videoUrl]; [self.playerItem addObserver:self forKeyPath:@"status" options:NSKeyValueObservingOptionNew context:nil];// 监听status属性 [self.playerItem addObserver:self forKeyPath:@"loadedTimeRanges" options:NSKeyValueObservingOptionNew context:nil];// 监听loadedTimeRanges属性 self.player = [AVPlayer playerWithPlayerItem:self.playerItem];<br>[[NSNotificationCenterdefaultCenter]addObserver:selfselector:@selector(moviePlayDidEnd:) name:AVPlayerItemDidPlayToEndTimeNotificationobject:self.playerItem];

先将在线视频链接存放在videoUrl中，然后初始化playerItem，playerItem是管理资源的对象（A player item manages the presentation state of an asset with which it is associated. A player item contains player item tracks—instances ofAVPlayerItemTrack—that correspond to the tracks in the asset.）

然后监听playerItem的status和loadedTimeRange属性，status有三种状态：

AVPlayerStatusUnknown,

AVPlayerStatusReadyToPlay,

AVPlayerStatusFailed

当status等于AVPlayerStatusReadyToPlay时代表视频已经可以播放了，我们就可以调用play方法播放了。

loadedTimeRange属性代表已经缓冲的进度，监听此属性可以在UI中更新缓冲进度，也是很有用的一个属性。

最后添加一个通知，用于监听视频是否已经播放完毕，然后实现KVO的方法：

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- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {     AVPlayerItem *playerItem = (AVPlayerItem *)object;     if ([keyPath isEqualToString:@"status"]) {         if ([playerItem status] == AVPlayerStatusReadyToPlay) {             NSLog(@"AVPlayerStatusReadyToPlay");             self.stateButton.enabled = YES;             CMTime duration = self.playerItem.duration;// 获取<span id="2_nwp" style="width: auto; height: auto; float: none;"><a id="2_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?rs=1&u=http%3A%2F%2Fwww%2Edaxueit%2Ecom%2Farticle%2F3407%2Ehtml&p=baidu&c=news&n=10&t=tpclicked3_hc&q=00007110_cpr&k=%CA%D3%C6%B5&k0=ios&kdi0=8&k1=%C8%ED%BC%FE&kdi1=8&k2=%C8%ED%BC%FE%BF%AA%B7%A2&kdi2=8&k3=%C6%BB%B9%FB&kdi3=8&k4=block&kdi4=8&k5=%CA%D3%C6%B5&kdi5=8&sid=2e3a805149a5f46f&ch=0&tu=u1704338&jk=6e6f3626bb79a9f4&cf=29&rb=0&fv=16&stid=9&urlid=0&luki=6&seller_id=1&di=128" target="_blank" mpid="2" style="text-decoration: none;"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">视频</span></a></span>总长度             CGFloat totalSecond = playerItem.duration.value / playerItem.duration.timescale;// 转换成秒             _totalTime = [self convertTime:totalSecond];// 转换成播放时间             [self customVideoSlider:duration];// 自定义UISlider外观             NSLog(@"movie total duration:%f",CMTimeGetSeconds(duration));             [self monitoringPlayback:self.playerItem];// 监听播放状态         } else if ([playerItem status] == AVPlayerStatusFailed) {             NSLog(@"AVPlayerStatusFailed");         }     } else if ([keyPath isEqualToString:@"loadedTimeRanges"]) {         NSTimeInterval timeInterval = [self availableDuration];// 计算缓冲进度         NSLog(@"Time Interval:%f",timeInterval);         CMTime duration = self.playerItem.duration;         CGFloat totalDuration = CMTimeGetSeconds(duration);         [self.videoProgress setProgress:timeInterval / totalDuration animated:YES];     } }   - (NSTimeInterval)availableDuration {     NSArray *loadedTimeRanges = [[self.playerView.player currentItem] loadedTimeRanges];     CMTimeRange timeRange = [loadedTimeRanges.firstObject CMTimeRangeValue];// 获取缓冲区域     float startSeconds = CMTimeGetSeconds(timeRange.start);     float durationSeconds = CMTimeGetSeconds(timeRange.duration);     NSTimeInterval result = startSeconds + durationSeconds;// 计算缓冲总进度     return result; }   - (NSString *)convertTime:(CGFloat)second{     NSDate *d = [NSDate dateWithTimeIntervalSince1970:second];     NSDateFormatter *formatter = [[NSDateFormatter alloc] init];     if (second/3600 >= 1) {         [formatter setDateFormat:@"HH:mm:ss"];     } else {         [formatter setDateFormat:@"mm:ss"];     }     NSString *showtimeNew = [formatter stringFromDate:d];     return showtimeNew; }

此方法主要对status和loadedTimeRanges属性做出响应，status状态变为AVPlayerStatusReadyToPlay时，说明视频已经可以播放了，这时我们可以获取一些视频的信息，包含视频长度等，把播放按钮设备enabled，点击就可以调用play方法播放视频了。在AVPlayerStatusReadyToPlay的底部还有个monitoringPlayback方法：

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- (void)monitoringPlayback:(AVPlayerItem *)playerItem {     self.playbackTimeObserver = [self.playerView.player addPeriodicTimeObserverForInterval:CMTimeMake(1, 1) queue:NULL usingBlock:^(CMTime time) {         CGFloat currentSecond = playerItem.currentTime.value/playerItem.currentTime.timescale;// 计算当前在第几秒         [self updateVideoSlider:currentSecond];         NSString *timeString = [self convertTime:currentSecond];         self.timeLabel.text = [NSString stringWithFormat:@"%@/%@",timeString,_totalTime];     }]; }

monitoringPlayback用于监听每秒的状态，- (id)addPeriodicTimeObserverForInterval:(CMTime)interval queue:(dispatch_queue_t)queue usingBlock:(void (^)(CMTime time))block;此方法就是关键，interval参数为响应的间隔时间，这里设为每秒都响应，queue是队列，传NULL代表在主线程执行。可以更新一个UI，比如进度条的当前时间等。

　　作为播放器，除了播放，暂停等功能外。还有一个必不可少的功能，那就是显示当前播放进度，还有缓冲的区域，我的思路是这样，用UIProgressView显示缓冲的可播放区域，用UISlider显示当前正在播放的进度，当然这里要对UISlider做一些自定义，代码如下：

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- (void)customVideoSlider:(CMTime)duration {     self.videoSlider.maximumValue = CMTimeGetSeconds(duration);     UIGraphicsBeginImageContextWithOptions((CGSize){ 1, 1 }, NO, 0.0f);     UIImage *transparentImage = UIGraphicsGetImageFromCurrentImageContext();     UIGraphicsEndImageContext();           [self.videoSlider setMinimumTrackImage:transparentImage forState:UIControlStateNormal];     [self.videoSlider setMaximumTrackImage:transparentImage forState:UIControlStateNormal]; }

这样UISlider就只有中间的ThumbImage了，而ThumbImage左右的颜色都变成透明的了，仅仅是用于显示当前的播放时间。UIProgressView则用于显示当前缓冲的区域，不做任何自定义的修改，在StoryBoard看起来是这样的：

把UISlider添加至UIProgressView上面，运行起来的效果就变成了这样：

这样基本的缓冲功能就做好了，当然还有一些功能没做，比如音量大小，滑动屏幕快进快退等，大家有时间可以自己做着玩儿下~ 最后的效果如下：

最后附上demo链接：https://github.com/mzds/AVPlayerDemo