详解iOS视频播放方式

// 初始化KRVideoPlayerController
- (instancetype)initWithFrame:(CGRect)frame
{
 self = [super init];
 if (self) {
 self.view.frame = frame;
 self.view.backgroundColor = [UIColor blackColor];
 self.controlStyle = MPMovieControlStyleNone;
 [self.view addSubview:self.videoControl];
 self.videoControl.frame = self.view.bounds;
 [self configObserver];
 [self configControlAction];
 }
 return self;
}
// 懒加载KRVideoPlayerControlView
- (KRVideoPlayerControlView *)videoControl
{
 if (!_videoControl) {
 _videoControl = [[KRVideoPlayerControlView alloc] init];
 }
 return _videoControl;
}

// 1、即将开始画中画
- (void)playerViewControllerWillStartPictureInPicture:(AVPlayerViewController *)playerViewController;
// 2、开始画中画
- (void)playerViewControllerDidStartPictureInPicture:(AVPlayerViewController *)playerViewController;
// 3、画中画失败
- (void)playerViewController:(AVPlayerViewController *)playerViewController failedToStartPictureInPictureWithError:(NSError *)error;
// 4、即将结束画中画
- (void)playerViewControllerWillStopPictureInPicture:(AVPlayerViewController *)playerViewController;
// 5、结束画中画
- (void)playerViewControllerDidStopPictureInPicture:(AVPlayerViewController *)playerViewController;

 

- (void)viewDidLoad {
 [super viewDidLoad];
 // Do any additional setup after loading the view.
 self.view.backgroundColor = [UIColor whiteColor]; 
 self.avPlayerItem = [AVPlayerItem playerItemWithURL:[NSURL URLWithString:MovieURL]];
 self.avPlayer = [[AVPlayer alloc]initWithPlayerItem:self.avPlayerItem];
 self.avPlayerLayer = [AVPlayerLayer playerLayerWithPlayer:self.avPlayer];
 self.avPlayerLayer.frame = CGRectMake(10, 100, 355, 200);
 [self.view.layer addSublayer:self.avPlayerLayer];
 // 添加观察者
 [self addObserverWithAVPlayerItem];
}
#pragma mark --
#pragma mark -- KVO
-(void)addObserverWithAVPlayerItem{
 //状态添加观察者
 [self.avPlayerItem addObserver:self forKeyPath:@"status" options:(NSKeyValueObservingOptionNew) context:nil];
 // 缓存进度添加观察者
 [self.avPlayerItem addObserver:self forKeyPath:@"loadedTimeRanges" options:NSKeyValueObservingOptionNew context:nil];
}
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
 AVPlayerItem * avplayeritem = (AVPlayerItem *)object;
 if ([keyPath isEqualToString:@"status"]) {
 AVPlayerStatus status = [[change objectForKey:@"new"] intValue];
 if (status == AVPlayerStatusReadyToPlay) {
  NSLog(@"准备好播放");
  CMTime duration = avplayeritem.duration;
  NSLog(@"视频总时长:%.2f",CMTimeGetSeconds(duration));
  // 播放
  [self.avPlayer play];
 }else if (status == AVPlayerStatusFailed){
  NSLog(@"视频准备发生错误");
 }else{
  NSLog(@"位置错误");
 }
 }else if ([keyPath isEqualToString:@"loadedTimeRanges"]){
  // 可以自定义缓存进度
  NSTimeInterval timeInterval = [self alreadyCacheVideoProgress];
  NSLog(@"视频已经缓存的时长:%.2f",timeInterval);
 }
}

#pragma mark --
#pragma mark -- alreadyCacheVideoProgress
-(NSTimeInterval)alreadyCacheVideoProgress{
 
 // 先获取到它的缓存的进度
 NSArray * cacheVideoTime = [self.avPlayerItem loadedTimeRanges];
 // CMTimeRange 结构体 start duration 表示起始位置 和 持续时间
 // 获取缓冲区域
 CMTimeRange timeRange = [cacheVideoTime.firstObject CMTimeRangeValue];
 float startSeconds = CMTimeGetSeconds(timeRange.start);
 float durationSeconds = CMTimeGetSeconds(timeRange.duration);
 // 计算总缓冲时间 = start + duration
 NSTimeInterval result = startSeconds + durationSeconds;
 return result;
} 

/*!
	@typedef	CMTime
	@abstract	Rational time value represented as int64/int32.
*/
typedef struct
{
	CMTimeValue	value;		/*! @field value The value of the CMTime. value/timescale = seconds. 帧数 */
	CMTimeScale	timescale;	/*! @field timescale The timescale of the CMTime. value/timescale = seconds.帧率（影片每秒有几帧）*/ CMTimeFlags flags; /*! @field flags The flags, eg. kCMTimeFlags_Valid, kCMTimeFlags_PositiveInfinity, etc. */  CMTimeEpoch epoch; /*! @field epoch Differentiates between equal timestamps that are actually different because of looping, multi-item sequencing, etc. Will be used during comparison: greater epochs happen after lesser ones. Additions/subtraction is only possible within a single epoch, however, since epoch length may be unknown/variable. */} CMTime;

CMTime duration = avplayeritem.duration;
NSLog(@"视频总时长:%.2f",CMTimeGetSeconds(duration));

- (id)addPeriodicTimeObserverForInterval:(CMTime)interval queue:(nullable dispatch_queue_t)queue usingBlock:(void (^)(CMTime time))block;

[self.avPlayer addPeriodicTimeObserverForInterval:CMTimeMake(1, 10) queue:dispatch_get_main_queue() usingBlock:^(CMTime time) {
  // CMTime的timescale的定义帮助理解下面代码
  // @field timescale The timescale of the CMTime. value/timescale = seconds.
  float currentPlayTime = (double)self.avPlayerItem.currentTime.value/ self.avPlayerItem.currentTime.timescale;
  NSLog(@"当前播放进度：%f",currentPlayTime);
 }];

/* Note that NSNotifications posted by AVPlayerItem may be posted on a different thread from the one on which the observer was registered. */

// notifications          description
AVF_EXPORT NSString *const AVPlayerItemTimeJumpedNotification			 NS_AVAILABLE(10_7, 5_0);	// the item's current time has changed discontinuously
AVF_EXPORT NSString *const AVPlayerItemDidPlayToEndTimeNotification NS_AVAILABLE(10_7, 4_0); // item has played to its end time
AVF_EXPORT NSString *const AVPlayerItemFailedToPlayToEndTimeNotification NS_AVAILABLE(10_7, 4_3); // item has failed to play to its end time
AVF_EXPORT NSString *const AVPlayerItemPlaybackStalledNotification NS_AVAILABLE(10_9, 6_0); // media did not arrive in time to continue playback
AVF_EXPORT NSString *const AVPlayerItemNewAccessLogEntryNotification	 NS_AVAILABLE(10_9, 6_0);	// a new access log entry has been added
AVF_EXPORT NSString *const AVPlayerItemNewErrorLogEntryNotification		 NS_AVAILABLE(10_9, 6_0);	// a new error log entry has been added

// notification userInfo key         type
AVF_EXPORT NSString *const AVPlayerItemFailedToPlayToEndTimeErrorKey NS_AVAILABLE(10_7, 4_3); // NSError