也许可以尝试子类化（不知道艺术作品是否有效）

class Fakemediaitem: MPMediaItem {
    override var persistentID: MPMediaEntityPersistentID {
        get {
            return self.localPersistentId
        }
    }
    
    override var albumTrackNumber: Int {
        get {
            return Int(self.localPersistentId)
        }
    }
    
    override var title: String {
        get {
            return "Fake title"
        }
    }
    
    private var localPersistentId: MPMediaEntityPersistentID
    
    init(_ id: MPMediaEntityPersistentID) {
        self.localPersistentId = id
        super.init()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}