hoge.m

char [AudioManager loadBgmData:](struct AudioManager *self, SEL selector, id bgm_data)
{
    NSError *has_occured;

    if (bgm_data == nil) return 0;

    self._bgmPlayer = [AVAudioPlayer alloc];
    [self._bgmPlayer initWithData: bgm_data error: &has_occured];

    if (has_occured == nil) {
        [self._bgmPlayer setDelegate:self];
        [self._bgmPlayer prepareToPlay];
        return 1;
    } else {
        return 0;
    }
}