初始化MPMusicPlayerMediaItemQueueDescriptor

Question

在一个函数中，如何初始化MPMusicPlayerMediaItemQueueDescriptor，作为Music Kit前置方法部分的第一步？我认为我需要我的媒体查询才能成为队列描述符，并且认为我需要对其进行初始化，但不确定如何！

[该类的苹果文档（https://developer.apple.com/documentation/mediaplayer/mpmusicplayermediaitemqueuedescriptor）建议我的函数应像这样：

    func playPlaylistNext(chosenPlaylist: String?) {
                var QueueDescriptor: MPMusicPlayerMediaItemQueueDescriptor
                let myMediaQuery = MPMediaQuery.songs()
                let predicateFilter = MPMediaPropertyPredicate(value: chosenPlaylist, forProperty: MPMediaPlaylistPropertyName)
                myMediaQuery.filterPredicates = NSSet(object: predicateFilter) as? Set<MPMediaPredicate>
                init(query: myMediaQuery) {
                        // What needs to go in here
                }
                    musicPlayerController.prepend(QueueDescriptor)
                }
            }

Answer 1

答案：

            let myMediaQuery = MPMediaQuery.songs()
            let predicateFilter = MPMediaPropertyPredicate(value: chosenPlaylist, forProperty: MPMediaPlaylistPropertyName)
            myMediaQuery.filterPredicates = NSSet(object: predicateFilter) as? Set<MPMediaPredicate>
            let qd: MPMusicPlayerMediaItemQueueDescriptor = .init(query: myMediaQuery)
            musicPlayerController.prepend(qd)