AVQueuePlayer 在线播放一组网络音频文件

头文件

@interface ZNAudioPlayerUtil : NSObject

//播放一组网络音频文件
+ (void)playAudios:(NSArray*)audioArr;
//终止播放
+ (void)stopPlayer;
//暂停播放
+ (void)pausePlayer;
//恢复播放
+ (void)resumePlayer;
//拖动到某个时间点
+ (void)seekToTime:(CMTime)time;
//当前播放时间
+ (CGFloat)currentTime;
//总时长
+ (CGFloat)totalTime;

@end

.m

static void* const AVLoopPlayerQueuePlayerStatusObservationContext = (void*)&AVLoopPlayerQueuePlayerStatusObservationContext;
static void* const AVLoopPlayerCurrentItemObservationContext = (void*)&AVLoopPlayerCurrentItemObservationContext;
static void* const AVLoopPlayerCurrentItemStatusObservationContext = (void*)&AVLoopPlayerCurrentItemStatusObservationContext;

@interface ZNAudioPlayerUtil(){
BOOL _addedObservers;
}

@property (nonatomic, strong) AVQueuePlayer *queuePlayer;
@property (nonatomic, assign) CGFloat totalDuration;

• (void)playbackInLoopWithURL:(NSString *)urlStr;
• (void)stopPlayback;

@end

@implementation ZNAudioPlayerUtil

• (instancetype)shareInstance{
  static ZNAudioPlayerUtil *player = nil;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
  player = [[ZNAudioPlayerUtil alloc]init];
  });
  return player;
  }

• (void)playAudios:(NSArray *)audioArr{
  [[ZNAudioPlayerUtil shareInstance] stopPlayback];
  for (NSString *audioID in audioArr) {
  NSString *urlStr = [NSString stringWithFormat:@”%@%@?id=%@”,EvHRServerHost,kHR_DownloadAudioFileUrl,audioID];
  [[ZNAudioPlayerUtil shareInstance] playbackInLoopWithURL:urlStr];
  }
  }

• (void)stopPlayer{
  [[ZNAudioPlayerUtil shareInstance] stopPlayback];
  }

• (instancetype)init{
  if (self = [super init]) {
  _queuePlayer = [[AVQueuePlayer alloc]init];
  }
  return self;

}

• (void)startObservingPlayerAndItem
  {
  if (_addedObservers == NO)
  {
  [_queuePlayer addObserver:self forKeyPath:@”status” options:NSKeyValueObservingOptionNew context:AVLoopPlayerQueuePlayerStatusObservationContext];
  [_queuePlayer addObserver:self forKeyPath:@”currentItem” options:NSKeyValueObservingOptionOld context:AVLoopPlayerCurrentItemObservationContext];
  [_queuePlayer addObserver:self forKeyPath:@”currentItem.status” options:NSKeyValueObservingOptionNew context:AVLoopPlayerCurrentItemStatusObservationContext];
  _addedObservers = YES;
  }
  }

• (void)stopObservingPlayerAndItem
  {
  if (_addedObservers)
  {
  [_queuePlayer removeObserver:self forKeyPath:@”status” context:AVLoopPlayerQueuePlayerStatusObservationContext];
  [_queuePlayer removeObserver:self forKeyPath:@”currentItem” context:AVLoopPlayerCurrentItemObservationContext];
  [_queuePlayer removeObserver:self forKeyPath:@”currentItem.status” context:AVLoopPlayerCurrentItemStatusObservationContext];
  _addedObservers = NO;
  }
  }

• (void)playbackInLoopWithURL:(NSString *)urlStr
  {
  AVURLAsset *asset = [AVURLAsset assetWithURL:[NSURL URLWithString:urlStr]];

  [asset loadValuesAsynchronouslyForKeys:@[@”duration”, @”playable”] completionHandler:^{
  /*
  The asset invokes its completion handler on an arbitrary queue when
  loading is complete. Because we want to access our AVQueuePlayer in our
  ensuing set-up, we must dispatch our handler to the main queue.
  */
  dispatch_async(dispatch_get_main_queue(), ^{
  NSError *durationError, *playableError;
  /*
  Check to make sure duration and playable properties are loaded
  before accessing them.
  */
  AVKeyValueStatus durationStatus = [asset statusOfValueForKey:@”duration” error:&durationError];
  AVKeyValueStatus playableStatus = [asset statusOfValueForKey:@”playable” error:&playableError];

      if (durationStatus == AVKeyValueStatusLoaded && playableStatus == AVKeyValueStatusLoaded )
      {
          if (CMTIME_COMPARE_INLINE([asset duration], >=, CMTimeMake(1,100)) && [asset isPlayable])
          {
              /*
               Based on the duration of the asset, we decide the number of
               player items to add to demonstrate gapless playback of the
               same asset.
               */
              NSUInteger countOfPlayerItems = (1.0 / CMTimeGetSeconds([asset duration])) + 2;
  

  // for (NSUInteger idx = 0; idx < countOfPlayerItems; ++idx)
  {
  AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset];
  if (playerItem)
  {
  [_queuePlayer insertItem:playerItem afterItem:nil];
  }
  }

              [self startObservingPlayerAndItem];
              [_queuePlayer play];
          }
          else
          {
              NSLog(@"Can't loop. Asset duration too short(%1.3f sec) or not playable(isPlayable: %s)",
                    CMTimeGetSeconds([asset duration]), ([asset isPlayable]?"YES":"NO"));
          }
      }
      else
      {
          if (durationStatus == AVKeyValueStatusFailed)
              NSLog(@"Failed to load duration property for asset: %@ with error: %@", asset, durationError);
  
          if (playableStatus == AVKeyValueStatusFailed)
              NSLog(@"Failed to load playable property for asset: %@ with error: %@", asset, playableError);
      }
  });
  

  }];
  }

• (void)observeValueForKeyPath:(NSString )keyPath ofObject:(id)object change:(NSDictionary )changeDictionary context:(void *)context
  {
  return;
  if (context == AVLoopPlayerQueuePlayerStatusObservationContext)
  {
  AVPlayerStatus newPlayerStatus = (AVPlayerStatus)[[changeDictionary objectForKey:NSKeyValueChangeNewKey] unsignedIntegerValue];
  if (newPlayerStatus == AVPlayerStatusFailed) {
  AVQueuePlayer player = (AVQueuePlayer )object;
  NSLog(@”End looping since player has failed with error %@”, player.error);
  [self stopPlayback];
  }

  }
  else if (context == AVLoopPlayerCurrentItemObservationContext)
  {
  AVQueuePlayer player = (AVQueuePlayer )object;

  if ([[player items] count] == 0)
  {
      NSLog(@"Play queue emptied out due to bad player item. End looping.");
      [self stopPlayback];
  }
  else
  {
      // Append the previous current item to the player's queue.
  

  // AVPlayerItem *itemRemoved = changeDictionary[NSKeyValueChangeOldKey];

      /*
       An initial change from a nil currentItem yields NSNull here. Check
       to make sure the class is AVPlayerItem before appending it to the
       end of the queue.
       */
  

  // if ([itemRemoved isKindOfClass:[AVPlayerItem class]])
  // {
  // [itemRemoved seekToTime:kCMTimeZero];
  // [self stopObservingPlayerAndItem];
  // [player insertItem:itemRemoved afterItem:nil];
  // [self startObservingPlayerAndItem];
  // }
  }
  }
  else if (context == AVLoopPlayerCurrentItemStatusObservationContext)
  {
  AVPlayerItemStatus newItemStatus = (AVPlayerItemStatus)[[changeDictionary objectForKey:NSKeyValueChangeNewKey] unsignedIntegerValue];
  if (newItemStatus == AVPlayerItemStatusFailed) {
  AVQueuePlayer player = (AVQueuePlayer )object;
  NSLog(@”End looping since player item has failed with error %@”, player.currentItem.error);
  [self stopPlayback];
  }
  }
  }

• (void)stopPlayback
  {
  [_queuePlayer pause];
  [self stopObservingPlayerAndItem];
  [_queuePlayer removeAllItems];
  }

pragma mark - public methods

• (void)pausePlayer{
  AVQueuePlayer *queuePalyer = [ZNAudioPlayerUtil shareInstance].queuePlayer;
  if (queuePalyer.timeControlStatus == AVPlayerTimeControlStatusPlaying) {
  [queuePalyer pause];
  }
  }

• (void)resumePlayer{
  AVQueuePlayer *queuePalyer = [ZNAudioPlayerUtil shareInstance].queuePlayer;
  if (queuePalyer.timeControlStatus == AVPlayerTimeControlStatusPaused) {
  [queuePalyer play];
  }
  }

• (void)seekToTime:(CMTime)time{
  AVQueuePlayer *queuePlayer = [ZNAudioPlayerUtil shareInstance].queuePlayer;
  if (queuePlayer) {
  [queuePlayer seekToTime:time];
  }
  }

• (CGFloat)currentTime{
  AVQueuePlayer *queuePlayer = [ZNAudioPlayerUtil shareInstance].queuePlayer;
  if (queuePlayer) {
  return [ZNAudioPlayerUtil totalTime] - CMTimeGetSeconds(queuePlayer.currentItem.currentTime);
  }
  return 0;
  }

• (CGFloat)totalTime{
  AVQueuePlayer *queuePlayer = [ZNAudioPlayerUtil shareInstance].queuePlayer;
  if (queuePlayer) {
  CGFloat totalDuration = 0;
  for (AVPlayerItem *item in queuePlayer.items) {
  CGFloat duration = CMTimeGetSeconds(item.duration);
  totalDuration += duration;
  }
  return totalDuration;
  }
  return 0;
  }

@end