var audioPlayer: AVAudioPlayer! @IBAction func playButtonPressed(_ sender: UIButton) { let sounds = ["x", "y", "z"].shuffled() guard let sound = sounds.shuffled(), let soundURL = Bundle.main.url(forResource: sound, withExtension: "mp3") else { return } do { audioPlayer = try AVAudioPlayer(contentsOf: soundURL) } catch { print(error) } audioPlayer.play()

Question

我在混洗声音时遇到问题。当我得到警惕let sound = sounds.shuffled（）时，我得到一个错误，条件绑定的初始化程序必须具有Optional类型，而不是'[String]'任何想法如何...

Answer 1

或者，您也可以删除混洗并使用

guard let sound = ["x", "y", "z"].randomElement()

sounds.shuffled()不会返回可选值，因此linter会告诉您不要对其进行保护，因为它没有任何意义。在这里阅读：https://developer.apple.com/documentation/swift/array/2994757-shuffled

Answer 2

guard let sound = sound.first, ... else { return }