Play background sound on iphone

Question

How to play background sound while my application is running?

Thanks.

Answer 1

Good. This is a background sound solution on iOS4 and iOS5 (it definitely works before iOS 5.0.1), and I tested it only with AVPlayer. It should probably work for MPMusicPlayerController as well.

Necessary framework:

• AVFoundation.framework
• AudioToolbox.framework

In Info.plistfor the key UIBackgroundModesadd audio.

In MyAppDelegate.h:

• reference <AVFoundation/AVFoundation.h>and<AudioToolbox/AudioToolbox.h>

• implement protocol AVAudioSessionDelegate:

  @interface MyAppDelegate : NSObject <UIApplicationDelegate, AVAudioSessionDelegate>
  

• define method ensureAudio:

  // Ensures the audio routes are setup correctly
  - (BOOL) ensureAudio;
  

In MyAppDelegate.m:

• implement the method ensureAudio:

  - (BOOL) ensureAudio
  {
      // Registers this class as the delegate of the audio session (to get background sound)
      [[AVAudioSession sharedInstance] setDelegate: self];  
  
      // Set category
      NSError *categoryError = nil;
      if (![[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&categoryError]) {
          NSLog(@"Audio session category could not be set"); 
          return NO;
      }
  
      // Activate session
      NSError *activationError = nil;
      if (![[AVAudioSession sharedInstance] setActive: YES error: &activationError]) {
          NSLog(@"Audio session could not be activated");
          return NO;
      }
  
      // Allow the audio to mix with other apps (necessary for background sound)
      UInt32 doChangeDefaultRoute = 1;
      AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(doChangeDefaultRoute), &doChangeDefaultRoute);
  
      return YES;
  }
  

• application:didFinishLaunchingWithOptions:, , [self ensureAudio]:

  - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
  {
      // Configure audio session
      [self ensureAudio];
  
      // Add the navigation controller view to the window and display.
      self.window.rootViewController = self.navigationController;
      [self.window makeKeyAndVisible];
  
      return YES;
  }
  

• AVAudioSessionDelegate :

  #pragma mark - AVAudioSessionDelegate
  
  - (void) beginInterruption
  {
  
  }
  
  - (void) endInterruption
  {
      // Sometimes the audio session will be reset/stopped by an interruption
      [self ensureAudio];
  }
  
  - (void) inputIsAvailableChanged:(BOOL)isInputAvailable
  {
  
  }
  

• , . ol '[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler], , , .

• ( , ARC, release):

  NSURL * file = [[NSBundle mainBundle] URLForResource:@"beep" withExtension:@"aif"];    
  AVURLAsset * asset = [[AVURLAsset alloc] initWithURL:file options:nil];
  AVPlayerItem * item = [[AVPlayerItem alloc] initWithAsset:asset];
  __block AVPlayer * player = [[AVPlayer alloc]initWithPlayerItem:item];
  __block id finishObserver = [[NSNotificationCenter defaultCenter] addObserverForName:AVPlayerItemDidPlayToEndTimeNotification 
                                                                        object:player.currentItem 
                                                                         queue:[NSOperationQueue mainQueue] 
                                                                    usingBlock:^(NSNotification *note) {
      [[NSNotificationCenter defaultCenter] removeObserver:finishObserver];
  
      // Reference the 'player' variable so ARC doesn't release it until it's
      // finished playing.
      player = nil;
  }];
  
  // Trigger asynchronous load
  [asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:^{
      // Start playing the beep (watch out - we're not on the main thread here)!
      [player play];
   }];
  

• shoooooooooooooo !

Answer 2

- setCategory AVAudioSessionCategoryPlayAndRecord.

[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayAndRecord error:&setCategoryErr];