Question

我在一个小应用程序上工作，我希望手机在我的位置控制器的事件上播放声音文件。问题是，当应用程序处于后台模式时，AVAudioPlayer不会启动音频文件，但会调度代码，获取NSLog输出。另一件事是它在模拟器中工作但不在手机上工作。

不是吗？

这是我播放文件的代码：

- (void)tryPlayTaleSound:(NSString*)fileName {

    NSString *backgroundMusicPath = [[NSBundle mainBundle] pathForResource:fileName ofType:@"mp3"];
    NSURL *backgroundMusicURL = [NSURL fileURLWithPath:backgroundMusicPath];
    NSError *error;

    backgroundMusicPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:backgroundMusicURL error:&error];

    // Check to see if iPod music is already playing
    //UInt32 propertySize = sizeof(otherMusicIsPlaying);
    //AudioSessionGetProperty(kAudioSessionProperty_OtherAudioIsPlaying, &propertySize, &otherMusicIsPlaying);

    // Play the music if no other music is playing and we aren't playing already
    //if (otherMusicIsPlaying != 1 && !backgroundMusicPlaying) {
    //[backgroundMusicPlayer prepareToPlay];
    [backgroundMusicPlayer play];
    backgroundMusicPlaying = YES;
    //}
    NSLog(@"%s - ", __FUNCTION__);
}

在日志中我得到了这个。

Apr 26 13:57:48 iPhone CommCenter[58] <Notice>: Client [com.apple.persistentconnection[dataaccessd,85]] is telling PDP context 0 to go active.
Apr 26 13:57:50 iPhone Herning100[1467] <Warning>: Playing audiofile - filename is Fil03
Apr 26 13:57:50 iPhone mediaserverd[39] <Warning>: 13:57:50.653 <AudioControl> WARNING translating CMSession error: -12985 
Apr 26 13:57:50 iPhone mediaserverd[39] <Warning>: 13:57:50.656 <AudioControl> WARNING translating CMSession error: -12985 
Apr 26 13:57:50 IPhone mediaserverd[39] <Error>: 13:57:50.734 <AudioControl> AudioQueue: Error -12985 from AudioSessionSetClientPlayState(1467)
Apr 26 13:57:50 iPhone Herning100[1467] <Warning>: -[AppDelegate tryPlayTaleSound:] - 
Apr 26 13:57:50 iPhone com.apple.debugserver-199[1465] <Warning>: 9 +28.832083 sec [05b9/0303]: error: ::mach_vm_region_recurse ( task = 0x1603, address => 0xfffffffe, size => 0, nesting_depth => 1024, info => 0x2fd7fe48, infoCnt => 12) addr = 0xfffffffe  err = (os/kern) invalid address (0x00000001)
Apr 26 13:57:51 iPhone com.apple.debugserver-199[1465] <Warning>: 10 +0.187961 sec [05b9/0303]: error: ::mach_vm_region_recurse ( task = 0x1603, address => 0xfffffffe, size => 0, nesting_depth => 1024, info => 0x2fd7fe48, infoCnt => 12) addr = 0xfffffffe  err = (os/kern) invalid address (0x00000001)

如果我使用AVAudioPlayer或AVAudioSession会有区别吗？

希望有人可以提供帮助。

/拉塞

Answer 1

除了audio中的后台模式Info.plist之外，您还需要将共享音频会话设置为适合您应用的模式，并在播放后台声音之前将其激活：

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *error = nil;
NSLog(@"Activating audio session");
if (![audioSession setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionDuckOthers error:&error]) {
    NSLog(@"Unable to set audio session category: %@", error);
}
BOOL result = [audioSession setActive:YES error:&error];
if (!result) {
    NSLog(@"Error activating audio session: %@", error);
}
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

完成播放声音后，不要忘记停用音频会话：

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *error = nil;
NSLog(@"Deactivating audio session");
BOOL result = [audioSession setActive:NO error:&error];
if (!result) {
    NSLog(@"Error deactivating audio session: %@", error);
}

Answer 2

在开始在后台播放声音之前，请设置后台任务。如果剩余的背景时间少于10秒，iOS似乎拒绝在后台启动声音。

Answer 3

在iOS上，只允许部分应用程序在后台运行。其中之一是音频播放器应用程序，但对于他们，您需要在Info.plist中设置“所需的背景模式”和“音频”（应用程序可以播放音频）。

如果您能够在后台获得位置，那么您必须在Plist中设置此键。在plist中添加音频权限。

IOS：在应用程序中播放声音

3 个答案: