Question

我在我的应用程序中使用SystemSound以播放简单的声音效果。除此之外，我通过MPMoviePlayerController播放音乐视频 - 现在当我上调/下调音量时，视频中的音乐会按预期响应（降低音量上调/下降）。

但播放的系统声音不会响应音量。当用户点击应用中的某些区域时，我正在播放系统。下面是我的代码片段：

- (void)handleTap:(UITapGestureRecognizer *)recognizer {
   SystemSoundID completeSound = nil;

   //yellow folder in xcode doesnt need subdirectory param
   //blue folder (true folder) will need to use subdirectory:@"dirname"
   NSURL *sound_path  = [[NSBundle mainBundle] URLForResource: target_sound_filename withExtension: @"wav"];

   AudioServicesCreateSystemSoundID((__bridge CFURLRef)sound_path, &completeSound);
   AudioServicesPlaySystemSound(completeSound);
}

PS。我仔细检查了我的“设置 - ＆gt;声音 - ＆gt;振铃和警报 - ＆gt;按钮更改”设置为ON（当我读到其他一些SO答案时，将此选项设置为OFF将导致系统响应无法响应音量按钮）

进一步使用systemound的原因是它在播放多个声音时给出了最准确和最敏感的结果（如在游戏中）。

如果可能，我倾向于不使用OpenAL（即使通过第三方声音库，如Finch或CocosDenshion）

有什么想法吗？

Answer 1

使用AVAudioPlayer课程播放由用户音量设置（非系统声音）控制的声音。

您可以为经常使用的每个声音文件保留AVAudioPlayer的实例，只需调用play方法即可。使用prepareToPlay预加载缓冲区。

Answer 2

向Marcus致敬，建议我可以为每个声音文件保留AVAudioPlayer的实例，并使用prepareToPlay预加载声音。它可能是为了帮助其他人寻找相同的解决方案，所以我就是这样做的（如果有人有改进的建议，请随时评论）

//top of viewcontroller.m
@property (nonatomic, strong) NSMutableDictionary *audioPlayers;
@synthesize audioPlayers = _audioPlayers;

//on viewDidLoad
self.audioPlayers = [NSMutableDictionary new];

//creating the instances and adding them to the nsmutabledictonary in order to retain them
//soundFile is just a NSString containing the name of the wav file
NSString *soundFile = [[NSBundle mainBundle] pathForResource:s ofType:@"wav"];
AVAudioPlayer *audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:soundFile] error:nil];
//audioPlayer.numberOfLoops = -1;
[audioPlayer prepareToPlay];

//add to dictonary with filename (omit extension) as key
[self.audioPlayers setObject:audioPlayer forKey:s];

//then i use the following to play the sound later on (i have it on a tap event)
//get pointer reference to the correct AVAudioPlayer instance for this sound, and play it
AVAudioPlayer *foo = [self.audioPlayers objectForKey:target_sound_filename];
[foo play];

//also im not sure how ARC will treat the strong property, im setting it to nil in dealloc atm.
-(void)dealloc {
    self.audioPlayers = nil;
}

ios SystemSound不会响应音量按钮

2 个答案: