分享一段Objective-C可调用的游戏中播放音乐

首先需要引入AudioTool 这个framework

- (id)initWithPath:(NSString *)path { UInt32 size, maxPacketSize; char *cookie; int i; if (gThereIsAnActiveTrack) { NSLog(@"*** WARNING *** GBMusicTrack only plays one track at a time! You must close the previously running track" " before you can play another. Requested track was: %@", [path lastPathComponent]); return nil; } //路径不存在的话返回空 if (path == nil) return nil; // 初始化　　 if(!(self = [super init])) return nil; // 通过指定的路径打开音乐 if (noErr != AudioFileOpenURL((CFURLRef)[NSURL fileURLWithPath:path], 0x01, 0, &audioFile)) { NSLog(@"*** Error *** GBMusicTrack - initWithPath: could not open audio file. Path given was: %@", path); return nil; } // 得到文件的数据类型 size = sizeof(dataFormat); AudioFileGetProperty(audioFile, kAudioFilePropertyDataFormat, &size, &dataFormat); // 创建一个新的队列，使用的是指定的特殊数据类型和回调缓存。 AudioQueueNewOutput(&dataFormat, BufferCallback, self, nil, nil, 0, &queue); // 如果需要的话读取包的大小并且分配所需要的空间 if (dataFormat.mBytesPerPacket == 0 || dataFormat.mFramesPerPacket == 0) { // since we didn't get sizes to work with, then this must be VBR data (Variable BitRate), so // we'll have to ask Core Audio to give us a conservative estimate of the largest packet we are // likely to read with kAudioFilePropertyPacketSizeUpperBound size = sizeof(maxPacketSize); AudioFileGetProperty(audioFile, kAudioFilePropertyPacketSizeUpperBound, &size, &maxPacketSize); if (maxPacketSize > gBufferSizeBytes) { maxPacketSize = gBufferSizeBytes; NSLog(@"*** Warning *** GBMusicTrack - initWithPath: had to limit packet size requested for file: %@", [path lastPathComponent]); } numPacketsToRead = gBufferSizeBytes / maxPacketSize; //给包的描述分配空间 packetDescs = malloc(sizeof(AudioStreamPacketDescription) * numPacketsToRead); } else { // 对于CBR 数据 (Constant BitRate), 使用合适的数据填充到混村中 numPacketsToRead = gBufferSizeBytes / dataFormat.mBytesPerPacket; // 这种包的描述不需要 packetDescs = nil; } // see if file uses a magic cookie (a magic cookie is meta data which some formats use) AudioFileGetPropertyInfo(audioFile, kAudioFilePropertyMagicCookieData, &size, nil); if (size > 0) { // 把缓存数据从文件中copy出来放到音频队列中 cookie = malloc(sizeof(char) * size); AudioFileGetProperty(audioFile, kAudioFilePropertyMagicCookieData, &size, cookie); AudioQueueSetProperty(queue, kAudioQueueProperty_MagicCookie, cookie, size); free(cookie); } AudioQueueAddPropertyListener(queue, kAudioQueueProperty_IsRunning, propertyListenerCallback, self); // 给特定的缓存分配数据 packetIndex = 0; for (i = 0; i < NUM_QUEUE_BUFFERS; i++) { AudioQueueAllocateBuffer(queue, gBufferSizeBytes, &buffers[i]); if ([self readPacketsIntoBuffer:buffers[i]] == 0)

稍微底层一点的函数，我们对此进行简单的封装，以至于可以更加方便的使用。

static  GBMusicTrack  * track;
static  NSMutableDictionary  * trackFiles;
static  BOOL enabled_ = TRUE;
static  BOOL musicVolume_ = 1.0f ;

//把音频文件按着名字添加到字典中

+ ( void ) addMusicTrack:(NSString * )filename name:(NSString * )name {
     if  (trackFiles  ==  nil) {
        trackFiles  =  [[NSMutableDictionary alloc] init];
    }
    [trackFiles setObject:filename forKey:name];
}

//通过判断字典中是否为空，看有没有音频文件。

+  (BOOL)hasMusicTrack:(NSString * )name {
    id obj  =  [trackFiles objectForKey:name];
     if (obj == nil)  return  FALSE;
     else
         return  TRUE;
}

//对上文提及的方法进行封装，参数是播放的名字，和是否重复播放

+  ( void )playMusicTrack:(NSString * )name withRepeat:(BOOL)b {
#ifndef DEBUG_NO_SOUND
     if  ( ! enabled_)  return ;
     if  (trackFiles  ==  nil)  return ;
    
     if (track != nil) {
        @try {
            [self stopCurrentTrack];
        }
        @catch (NSException *  ex) {
            NSLog([ex description]);
        }
    }

// 这个函数initWithPath就是上文提及的，初始化方法。

//
    track  =  [[GBMusicTrack alloc] initWithPath:[[NSBundle mainBundle] 
                                                pathForResource:[trackFiles objectForKey:name] 
                                                ofType: @" mp3 " ]];
    [track setRepeat:b];
    [track setVolume:musicVolume_];

// 音乐的播放

 

  [track play];
#endif
}