切换视图控制器时的连续音乐播放. Swift 4.2

Question

我正在尝试将背景音乐实现到我用Xcode制作的应用程序中，在我使用的Swift的当前版本(4.2)中，我很难找到一个有效的解决方案。当前，当我从一个视图控制器切换到另一个视图控制器时，音乐将重新启动，但当我退出视图控制器时，这不会发生。

我将发布我目前正在编写的代码：

ViewController.swift

import UIKit
import AVFoundation

class ViewController: UIViewController {

var audioPlayer : AVAudioPlayer?
var selectedSoundFileName : String = ""
let phonicSoundArray = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "ai", "ar", "ch", "ck", "ee", "ie", "ng", "oa", "oi", "oo", "or", "ou", "ph", "qu", "sh", "ss", "th", "ue"]

override func viewDidLoad() {
    super.viewDidLoad()
    MusicHelper.sharedHelper.playBackgroundMusic()
}


@IBAction func dismissCurrentView(_ sender: Any) {
    self.dismiss(animated: true, completion: nil)
}

//== Phonic audio playback =================
@IBAction func phonicPracticeButtonPressed(_ sender: AnyObject) {

    selectedSoundFileName = phonicSoundArray[sender.tag - 1]+".mp3"

    let path = Bundle.main.path(forResource: selectedSoundFileName, ofType:nil)!
    let url = URL(fileURLWithPath: path)

    do {
        audioPlayer = try AVAudioPlayer(contentsOf: url)
        audioPlayer?.play()
    } catch {
        print("Couldn't load audio")
    }
}
}

BGMSingleton.swift

import Foundation
import AVFoundation

class MusicHelper {
static let sharedHelper = MusicHelper()
var audioPlayer: AVAudioPlayer?

func playBackgroundMusic() {
    let aSound = NSURL(fileURLWithPath: Bundle.main.path(forResource: "BGM", ofType: "mp3")!)
    do {
        audioPlayer = try AVAudioPlayer(contentsOf:aSound as URL)
        audioPlayer!.numberOfLoops = -1
        audioPlayer!.prepareToPlay()
        audioPlayer!.play()
    }
    catch {
        print("Cannot play the file")
    }
}
}

Answer 1

假设你在你发布的两个相同的风投之间.

每当你在VC中加入MusicHelper.sharedHelper.playBackgroundMusic()时，你的音乐就会重新启动。

viewDidLoad在VC生命周期中只发生一次。当你解雇一个VC时，你不会调用它的viewDidLoad，这就是为什么音乐没有重新启动的原因。

关于VC生命周期的更多信息

https://developer.apple.com/documentation/uikit/uiviewcontroller

Looking to understand the iOS UIViewController lifecycle