为下一个队列(MediaPlayer)洗牌NSMutableArray和“洗牌专辑”？

Question

我已经成功地创建了一个工作(几乎)完美的下一个排队系统。我可以移动，删除和添加歌曲到名单上，根本没有任何问题。我遇到的唯一问题是，当用户决定使用洗牌模式(例如MPMusicShuffleMode.Songs)时，up next视图仍然显示旧的顺序(假设洗牌模式设置为off)。应用程序Ecoute有一个类似的排队系统，但它也可以在洗牌时工作。

我已经意识到，Ecoute不使用MPMusicShuffleMode，如果您进入股票音乐播放器后，按洗牌在埃库特，它保持不变。我想出了一种方法来显示洗牌歌曲的正确顺序(只需洗牌NSMutableArray并将其设置为新队列)。真正的问题是，当用户想要“洗牌专辑”时，我该如何调整这个数组呢？如果这有帮助的话，NSMutableArray包含MPMediaItem。

非常感谢。

编辑：

这一尝试奏效了，但随着歌曲数量的增加，时间呈指数增长。2000首歌花了25到35秒，非常慢。

else if(self.shuffleMode == "Songs"){
        self.shuffleMode = "Albums"
        self.shuffle.setTitle("Shuffle Albums", forState: UIControlState.Normal)
        var queueCopy = NSMutableArray(array: self.queue.items)
        var newQueue = NSMutableArray(array: [])

        var albums = MPMediaQuery.albumsQuery().collections as [MPMediaItemCollection]
        var albumsCopy = NSMutableArray(array: albums)
        shuffleArray(albumsCopy)

        for album in albumsCopy{
            for item in queueCopy{
                if (album.representativeItem!.valueForProperty(MPMediaItemPropertyAlbumTitle) as NSString == item.valueForProperty(MPMediaItemPropertyAlbumTitle) as NSString){
                    for(var i = 0; i < album.items!.count; i++){
                        if(album.items![i].valueForProperty(MPMediaItemPropertyTitle) as NSString == item.valueForProperty(MPMediaItemPropertyTitle) as NSString){
                            newQueue.addObject(item as MPMediaItem)
                        }
                    }
                }
            }
        }

        let newQueueToSet = MPMediaItemCollection(items: newQueue)
        let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
        appDelegate.currentQueue = newQueueToSet
        self.queue = newQueueToSet

        self.player.setQueueWithItemCollection(newQueueToSet)

}

编辑2：

成功地把它降到了8秒，但远没有接近Ecoute的1到2秒。

8第二版：

        var albumNames = [String]()
        for item in queueCopy{
            albumNames.append(item.valueForProperty(MPMediaItemPropertyAlbumTitle) as NSString)
        }

        let unique = NSSet(array: albumNames).allObjects as [MPMediaItem]
        var uniqueAlbumNames = NSMutableArray(array: unique)
        shuffleArray(uniqueAlbumNames)

        for name in uniqueAlbumNames{
            for item in queueCopy{
                if item.valueForProperty(MPMediaItemPropertyAlbumTitle) as NSString == name as NSString{
                    newQueue.addObject(item as MPMediaItem)
            }
        }
}

最后编辑：

我坚持的最后一段代码。大约需要7-8秒，近3000首歌曲。

    @IBAction func shufflePressed(sender: AnyObject) {

    if self.shuffleMode == "Off"{
        self.shuffleMode = "Songs"
        self.shuffle.setTitle("Shuffle All", forState: UIControlState.Normal)
        self.shuffle.setTitle("Shuffling", forState: UIControlState.Highlighted)


        var queueCopy = NSMutableArray(array: self.queue.items)
        self.unshuffledQueueCopy = self.queue

        shuffleArray(queueCopy)
        let newQueue = MPMediaItemCollection(items: queueCopy)
        let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
        appDelegate.currentQueue = newQueue
        self.queue = newQueue

        self.player.setQueueWithItemCollection(newQueue)

    }
    else if(self.shuffleMode == "Songs"){
        self.shuffleMode = "Albums"
        self.shuffle.setTitle("Shuffle Albums", forState: UIControlState.Normal)

        var queueCopy = NSMutableArray(array: self.queue.items)
        var newQueue = NSMutableArray(array: [])

        var albums = MPMediaQuery.albumsQuery().collections as [MPMediaItemCollection]
        var albumsCopy = NSMutableArray(array: albums)
        shuffleArray(albumsCopy)


        // Takes 8 seconds for 3000 songs

        var albumNames = [String]()

        for item in queueCopy{
            albumNames.append(item.valueForProperty(MPMediaItemPropertyAlbumTitle) as NSString)
        }

        let unique = NSSet(array: albumNames).allObjects as [MPMediaItem]
        var uniqueAlbumNames = NSMutableArray(array: unique)
        shuffleArray(uniqueAlbumNames)


        for name in uniqueAlbumNames{
            for item in queueCopy{
                if item.valueForProperty(MPMediaItemPropertyAlbumTitle) as NSString == name as NSString{
                    newQueue.addObject(item as MPMediaItem)
                }
            }
        }

        let newQueueToSet = MPMediaItemCollection(items: newQueue)
        let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
        appDelegate.currentQueue = newQueueToSet
        self.queue = newQueueToSet

        self.player.setQueueWithItemCollection(newQueueToSet)

    }
    else if(self.shuffleMode == "Albums"){
        self.shuffleMode = "Off"
        self.shuffle.setTitle("Shuffle", forState: UIControlState.Normal)
        var queueCopy = NSMutableArray(array: self.unshuffledQueueCopy.items)
        var nowPlayingItem = self.player.nowPlayingItem
        for(var i = 0; i < queueCopy.count; i++){
            if(queueCopy[i] as MPMediaItem == nowPlayingItem){
                self.fromIndex = i
            }
        }
        let newQueue = MPMediaItemCollection(items: queueCopy)
        let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
        appDelegate.currentQueue = newQueue
        self.queue = newQueue

        self.player.setQueueWithItemCollection(newQueue)
        self.fromItem = newQueue.items[fromIndex + 1] as MPMediaItem

    }

Answer 1

因此，在伪代码中，它看起来如下所示。

1. 循环数组，只生成一个新的专辑数组
2. 洗牌新专辑数组
3. 循环新专辑数组，查看该相册中项目的原始数组。
4. 在比赛中，将这些歌曲写到第三个数组中，这将成为你的新播放列表。

谢谢