SimpleAudioEngine shuffle playlist

i want to shuffle a dozen of songs in my game. Next song should not be the same as current song.

[[[SimpleAudioEngine sharedEngine] playBackgroundMusic: song];

There should be a loop and song should be randomized,

[[NSString stringWithFormat: @"song%i.mp3", arc4random() % 20 + 1];
//2开发者_开发技巧0 songs starting from song1.mp3

It would be great if the song will stop playing when the user's ipod music is playing. But the sound effect should still be available:

[[SimpleAudioEngine sharedEngine] playEffect: @"aaa.caf"]

Also, when the ipod music is playing, then launch the game, game music should not even be started.

How to implement this?

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When you start your app, you can check like this and play or not your own music.

if ([[MPMusicPlayerController iPodMusicPlayer] playbackState] == MPMusicPlaybackStatePlaying) {
    // dont play and do whatever you think should be done in this case
} else {
    [[[SimpleAudioEngine sharedEngine] playBackgroundMusic: song];
}

Side note:

//Remember to preload your effects and bg music so there is not any delay
[[SimpleAudioEngine sharedEngine] preloadEffect:@"aaa.caf"];
[[SimpleAudioEngine sharedEngine] preloadBackgroundMusic:@"song1.mp3"];
//And to unload your effects when you wont use them anymore or receive a mem warning, or in dealloc
[[SimpleAudioEngine sharedEngine] unloadEffect:@"aaa.caf"];

UPDATE

In viewDidLoad, create an strings array with all your songs and shuffle them with: [self shuffle],for this implement this code:

- (void)shuffle {
    for (NSInteger i = [songsArray count] - 1; i > 0; --i) [songsArray exchangeObjectAtIndex:(arc4random() % (i+1)) withObjectAtIndex:i];
}

Every time your background music finishes use [self shuffle] and then playBackgroundMusic:[songsArray lastObject] that should take care of your shuffled playlist.