如何在两个类之间传递 IBOutlet？

Question

我有一个 class 用于管理 AVPlayer 和 ViewController 显示 AVPlayer。在 ViewController 我有 3 IBOutlets:

@IBOutlet weak var playButton: UIButton!
@IBOutlet weak var progressBar: UIProgressView!
@IBOutlet weak var timerLabel: UILabel!

问题是我不知道如何将 IBOutlets 从 ViewController 传递给我的玩家管理 class。我总是得到 nil 和

fatal error: unexpectedly found nil while unwrapping an Optional value

初始化时 progressBar、timerLabel 或 playButton。

这是我的播放器管理 class:

的一些代码

import UIKit
import AVFoundation

class RecordsAudioPlayer: NSObject
{
    var player = AVPlayer()
    var timerUpdateAudioProgressView = Timer()
    var timerUpdateTime = Timer()
    var isPlaying: Bool = false

...

func updateAudioProgressView()
    {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let vc = storyboard.instantiateViewController(withIdentifier: "callRecords") as! CallRecordsViewController

        let progressBar = vc.progressBar! 
        print("method fired: updateAudioProgressView ", NSDate.init(timeIntervalSinceNow: 0).description)
        if isPlaying
        {
            let currentPlayerItem = player.currentItem
            let duration = Float((currentPlayerItem?.asset.duration.value)!)/Float((currentPlayerItem?.asset.duration.timescale)!)
            let currentTime = Float(player.currentTime().value)/Float(player.currentTime().timescale)
            progressBar.setProgress(Float(currentTime/duration), animated: false)
        }
    }

    func updateTime()
    {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let vc = storyboard.instantiateViewController(withIdentifier: "callRecords") as! CallRecordsViewController
        let timerLabel: UILabel! = vc.timerLabel! //***I get exception here
        print("method fired: updateTime ", NSDate.init(timeIntervalSinceNow: 0).description)
        let currentTime = Int64(player.currentTime().value)/Int64(player.currentTime().timescale)
        let minutes = currentTime / 60
        let seconds = currentTime - minutes * 60
        timerLabel.text = String(format: "%02d : %02d", Int(minutes), Int(seconds))
    }

Answer 1

加载视图后立即建立出口连接 - 这通常会延迟到呈现视图时。

您可以通过调用 vc.loadViewIfNeeded()（其中 vc 是您的视图控制器）来强制执行此操作

但不太确定您的 updateAudioProgressView 和 updateTime 的实现是否真的如您所愿：它们总是创建 new 视图控制器并更新它们的 subviews/outlets。这些新创建的视图控制器甚至不会显示（或者您只是跳过了演示代码）。如果您打算更新现有的视图控制器，则必须执行其他操作（例如，提交要更新的视图控制器）。

还有一点：强烈建议您不要按照自己的方式做事。视图控制器应该是唯一更新其出口的控制器。其他任何人都应该只更新视图控制器的属性（比如设置当前进度、时间值等），然后通知视图控制器更新自身。然后视图控制器将按照它想要的方式更新它的呈现插座。

Answer 2

在这种情况下，代表们是来救我们的。为您的 RecordsAudioPlayer class 创建委托方法。并使用它们来更新进度条和计时器标签。

protocol RecordsAudioPlayerDelegate
{
  func audioplayerProgressUpdated(time:CGFloat) // change the method as your wish
}

class RecordsAudioPlayer: NSObject
{
  var delegate:RecordsAudioPlayerDelegate?
  var player = AVPlayer()
  var timerUpdateAudioProgressView = Timer()
  var timerUpdateTime = Timer()
  var isPlaying: Bool = false
    ...
    ...
    ...

  //Call the delegate method from where you get the player current time
  self.delegate.audioplayerProgressUpdated(playerTime)

  //For controlling play/pause using play button 
  func playButtonClicked()
  {
    //play/pause player based on player status
  }
}

并在您的 ViewController while/after 中创建 RecordsAudioPlayer 对象并将委托设置为 self

class YourViewController : UIViewController, RecordsAudioPlayerDelegate
{
  var recordsAudioPlayer : RecordsAudioPlayer!

  // set delegate where you create object for RecordsAudioPlayer
  self.recordsAudioPlayer.delegate = self

  //Now implement the delegate function
  func audioplayerProgressUpdated(time:CGFloat)
  {
   //update progress view and timer label
  }

  //And inside from the play button action method 
  @IBAction func playButtonClicked(sender: UIButton)
  {
   self.recordsAudioPlayer.playButtonClicked()
  }

}

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