ios - 类型 'string' 没有成员 'playback'

Question

尝试在 xcode 10.1 中构建木琴时，在 iOS12 上使用 swift 4.2，我使用按钮播放 .wav 文件并输入以下代码，但出现以下错误:

"type 'String' has no member 'playback'"

func playSound() {
        guard let url = Bundle.main.url(forResource: "soundName", withExtension: "mp3") else { return }

        do {
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: [])
            try AVAudioSession.sharedInstance().setActive(true)

            /* The following line is required for the player to work on iOS 11. Change the file type accordingly*/
            player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileType.mp3.rawValue)

            /* iOS 10 and earlier require the following line:
             player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileTypeMPEGLayer3) */

            guard let player = player else { return }

            player.play()

        } catch let error {
            print(error.localizedDescription)
        }
    }

Answer 1

我四处查看 StackOverflow 并借用了这段有效的代码，但我不知道它是否是传统的做法。

swift 4.2

import AVFoundation
var player = AVAudioPlayer()

let url = URL(fileURLWithPath: Bundle.main.path(forResource: "note1", ofType: "wav")!)
    do {
        player = try AVAudioPlayer(contentsOf: url)
        player.play()
    } catch {
        print("couldn't load file :(")
    }