AVPlayer獲取元數據但不播放

Question

我試圖做一個非常簡單的應用程序，目的是偵聽音頻流（AAC 64 kbps）。要做到這一點我使用AVPlayer從Apple AVFoundation一直遵循：

ViewController.m

#import "ViewController.h" 
@interface ViewController() 
@end 

@implementation ViewController 
@synthesize playerItem, player; 

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

- (void) viewWillAppear:(BOOL)animated{ 
    [super viewWillAppear:animated]; 
    playerItem = [AVPlayerItem playerItemWithURL:[NSURL URLWithString:@"http://stream.myjungly.fr/MYJUNGLY2"]]; 
    [playerItem addObserver:self forKeyPath:@"timedMetadata" options:NSKeyValueObservingOptionNew context:nil]; 

    player = [AVPlayer playerWithPlayerItem:playerItem]; 
    [player play]; 

    NSLog(@"player item error : %@", playerItem.error.description); 
    NSLog(@"player error : %@", player.error.description); 
} 

- (void) observeValueForKeyPath:(NSString*)keyPath ofObject:(id)object 
        change:(NSDictionary*)change context:(void*)context { 

    if ([keyPath isEqualToString:@"timedMetadata"]) 
    { 
     AVPlayerItem* _playerItem = object; 
     for (AVMetadataItem* metadata in _playerItem.timedMetadata) 
     { 
      NSLog(@"\nkey: %@\nkeySpace: %@\ncommonKey: %@\nvalue: %@", [metadata.key description], metadata.keySpace, metadata.commonKey, metadata.stringValue); 
     } 
    } 
} 

@end 

我的目標player和playerItem是強屬性：

ViewController.h

@interface ViewController : UIViewController 

@property (nonatomic, strong) AVPlayerItem* playerItem; 
@property (nonatomic, strong) AVPlayer* player; 

@end 

鍵值觀察是偉大的工作，這是我的日誌：

2013-05-14 11:18:03.725 MusicAvPlayer[6494:907] player item error : (null) 
2013-05-14 11:18:03.728 MusicAvPlayer[6494:907] player error : (null) 
2013-05-14 11:18:08.140 MusicAvPlayer[6494:907] 
key: title 
keySpace: comn 
commonKey: title 
value: Alabama Shakes - Be Mine 

但音頻無法播放，我有去沒聲音！任何想法爲什麼？

編輯：我已經看這個問題：

No sound coming from AVPlayer

AVAudioPlayer, No Sound

AVAudioPlayer not playing any sound

這就是爲什麼我使用的是強大的屬性，所以我想我的問題是，不與ARC相關

Answer 1

我發現了問題：iPhone在靜音模式......所以沒有聲音可以走出去，在揚聲器的聲音被打時，我用的是頭電話。

但是我現在有一個新的問題：當手機處於靜音模式時，如何在揚聲器上播放聲音？ （如官方音樂應用程序）

編輯：...答案是有： Play sound on iPhone even in silent mode

Answer 2

// Init PlayerItem 
playerItem = [AVPlayerItem playerItemWithURL:[NSURL URLWithString:@"http://stream.myjungly.fr/MYJUNGLY2"]]; 

// Init Player Obj 
player = [AVPlayer playerWithPlayerItem:playerItem]; 
// Add objserver on Player 
[player addObserver:self forKeyPath:@"status" options:0 context:nil]; 

添加觀測器方法的類

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object 
         change:(NSDictionary *)change context:(void *)context { 
    if (object == player && [keyPath isEqualToString:@"status"]) { 
     if (player.status == AVPlayerStatusReadyToPlay) { 
      // Start playing... 
      [player play]; 
     } else if (player.status == AVPlayerStatusFailed) { 
      // something went wrong. player.error should contain some information 
     } 
    } 
    if ([keyPath isEqualToString:@"timedMetadata"]) 
    { 
     AVPlayerItem* _playerItem = object; 
     for (AVMetadataItem* metadata in _playerItem.timedMetadata) 
     { 
      NSLog(@"\nkey: %@\nkeySpace: %@\ncommonKey: %@\nvalue: %@", [metadata.key description], metadata.keySpace, metadata.commonKey, metadata.stringValue); 
     } 
    } 

}