iPhone 应用程序：未在 AVAudio Player 中恢复音频会话

Question

在我的 iPhone 应用程序中，我使用 AVAudioPlayer 播放音乐。当我的应用程序在后台运行时，它也在运行，因为我

在 AppDelegate 中编写了这段代码，

-- application didFinishLaunchingWithOptions

  audioManager= [[AudioManager alloc] init];
  audioManager.delegate=self;
   audioManager.soundFile=[[[NSBundle mainBundle] pathForResource:@"mysong" ofType:@"wav"] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
  [audioManager setFileForPlay];
  [audioManager.player setNumberOfLoops:-1];
  [audioManager.player setVolume:.5];
  [audioManager play];



 -(void) playerBeginInterruption:(AVAudioPlayer *)p{


[usdef setValue:@"START" forKey:@"LOCATIONMANAGER"];

[locationManager startUpdatingLocation];
[p pause];
// audioManager=nil;

  }

 -(void) playerBeginInterruptionInBackground:(AVAudioPlayer *)p{

 [usdef setValue:@"START" forKey:@"LOCATIONMANAGER"];
[locationManager startUpdatingLocation];
[p pause];
//audioManager=nil;

}

 -(void) playerEndInterruption:(AVAudioPlayer *)p{
 NSLog(@"Inteerpt END");

  [p prepareToPlay];
  [p play];
  [usdef setValue:@"STOP" forKey:@"LOCATIONMANAGER"];



}

 -(void) playerEndInterruptionInBackgroud:(AVAudioPlayer *)p{
  NSLog(@"Inteerpt END BG");
 // [self performSelector:@selector(allocaudioManager)];  
  [p prepareToPlay];
  [p play];

  [usdef setValue:@"STOP" forKey:@"LOCATIONMANAGER"];
  // [locationManager stopUpdatingLocation];

}

现在我已经为处理委托方法的音频管理器创建了单独的类。

在 .h 文件中

  #import <Foundation/Foundation.h>
  #import <AudioToolbox/AudioToolbox.h>
#import <AVFoundation/AVFoundation.h>
 @protocol AudioManagerDelegate;
 @interface AudioManager : NSObject <AVAudioPlayerDelegate> {
AVAudioPlayer                       *player;

NSString                            *soundFile;
BOOL                                inBackground;
id<AudioManagerDelegate>            delegate;

 }
@property (nonatomic, assign)   id<AudioManagerDelegate>delegate;
@property (nonatomic, retain)   NSString        *soundFile;

@property (nonatomic, assign)   AVAudioPlayer   *player;
@property (nonatomic, assign)   BOOL            inBackground;
 - (void)play;
 - (void)pause;
 - (void)stop;
 - (void)registerForBackgroundNotifications;
 -( void) setFileForPlay;
  @end
  @protocol AudioManagerDelegate <NSObject>
  @optional
   - (void)playerDidFinishPlayingInBackground:(AVAudioPlayer*)p;
  - (void)playerDidFinishPlaying:(AVAudioPlayer*)p;
  - (void)playerBeginInterruption:(AVAudioPlayer*)p;
  - (void)playerBeginInterruptionInBackground:(AVAudioPlayer*)p;
  - (void)playerEndInterruption:(AVAudioPlayer *)p;
   - (void)playerEndInterruptionInBackgroud:(AVAudioPlayer *)p;
 @end

在 .m 文件中

    @implementation AudioManager
  @synthesize delegate;
  @synthesize player;
  @synthesize inBackground;
  @synthesize soundFile;
  
   void RouteChangeListener(void *inClientData, AudioSessionPropertyID  inID,UInt32 inDataSize, const void *inData);

 -(id) init
{
     if((self=[super init]))
    {
    
    OSStatus result = AudioSessionInitialize(NULL, NULL, NULL, NULL);
    if (result)
        NSLog(@"Error initializing audio session! %ld", result);
    
    [[AVAudioSession sharedInstance] setDelegate: self];
    NSError *setCategoryError = nil;
    [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error: &setCategoryError];
    if (setCategoryError)
        NSLog(@"Error setting category! %@", setCategoryError);
    
    result = AudioSessionAddPropertyListener (kAudioSessionProperty_AudioRouteChange, RouteChangeListener, self);
    if (result) 
        NSLog(@"Could not add property listener! %ld", result);
    
    return self;
}
return nil;
 }


 -(void) setFileForPlay{
     self.player=nil;
       player = [[AVAudioPlayer alloc]   initWithData:[NSData dataWithContentsOfFile:self.soundFile] error:nil];//initWithContentsOfURL:[NSURL URLWithString:self.soundFile]  error:nil];

    if (self.player)
     {
          player.delegate = self;
      }

   }


 -(void) play{

  [self.player play];

  }
  -(void)pause{
    [self.player pause];
    NSLog(@"in Pause");
  }
 -(void)stop{
    [self.player stop];
     NSLog(@"in stop");
  }



              void RouteChangeListener(void *inClientData, AudioSessionPropertyID   inID,UInt32 inDataSize, const void *inData){
      AudioManager* This = (AudioManager*)inClientData;

        if (inID == kAudioSessionProperty_AudioRouteChange) {
    
        CFDictionaryRef routeDict = (CFDictionaryRef)inData;
    NSNumber* reasonValue = (NSNumber*)CFDictionaryGetValue(routeDict, CFSTR(kAudioSession_AudioRouteChangeKey_Reason));
    
    int reason = [reasonValue intValue];
    
    if (reason == kAudioSessionRouteChangeReason_OldDeviceUnavailable) {
         
        [This stop];
    }
}

  }
   - (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)p successfully:(BOOL)flag
    {
if (flag == NO)
    NSLog(@"Playback finished unsuccessfully");

[p setCurrentTime:0.];
if (inBackground)
{
    [delegate playerDidFinishPlayingInBackground:p];
}
else
{
    [delegate playerDidFinishPlaying:p];
}
    }
     - (void)playerDecodeErrorDidOccur:(AVAudioPlayer *)p error:(NSError *)error
   {
NSLog(@"ERROR IN DECODE: %@\n", error); 
    }
  // we will only get these notifications if playback was interrupted
  - (void)audioPlayerBeginInterruption:(AVAudioPlayer *)p
    {
NSLog(@"Interruption begin ");
// the object has already been paused,  we just need to update UI
if (inBackground)
{
    [delegate playerBeginInterruptionInBackground:p];
}
else
{
    [delegate playerBeginInterruption:p];
}

    }


     - (void)audioPlayerEndInterruption:(AVAudioPlayer *)p withFlags:(NSUInteger)flags
    {
    if(inBackground)
      {
      [delegate playerEndInterruptionInBackgroud:p];
    }
        else
    {
    [delegate playerEndInterruption:p];
    }
        NSLog(@"Interruption ended. Resuming playback");
     }

    - (void)registerForBackgroundNotifications
    {
[[NSNotificationCenter defaultCenter] addObserver:self
                                                    selector:@selector(setInBackgroundFlag)
                                                   name:UIApplicationWillResignActiveNotification
                                             object:nil];

      [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(clearInBackgroundFlag)
                                               name:UIApplicationWillEnterForegroundNotification
                                           object:nil];
  }

 - (void)setInBackgroundFlag
   {
inBackground = true;
   }

- (void)clearInBackgroundFlag
   {
inBackground = false;
   }

   @end

现在的问题是，如果我正在播放 iPod 库中的任何歌曲并停止该歌曲并关闭 iPod 库，我在启动 ipos 库之前播放的原始 avaudioplayer 不会恢复意味着它没有播放歌曲再次。

可能出什么问题了？

是否有任何可以提供帮助的演示项目或示例代码？

Answer 1

您不必在 audioPlayerBeginInterruption: 播放器中的 AVAudioPlayer（代码中的 p）上调用 pause由于中断，不应在该阶段进行比赛。在 audioPlayerEndInterruption: 中，以下内容通常对我有用：

[p prepareToPlay];
[p play];

Audio Session Cookbook 有一个关于“使用 AVAudioPlayer 处理中断类”也应该有帮助。