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
}