将代码更新到 xcode 9 和 swift 4 后应用程序崩溃

Question

将项目升级到 xcode 9 和 swift 4 后应用程序崩溃。在调试时

    backview.addsubview(stackview)

应用程序因 libc++abi.dylib 崩溃：以 NSException 类型的未捕获异常终止。 代码在 swift 3 中完美运行。但在迁移到 swift 4 后它崩溃了。这是我的全部功能。

    var isAlreadyThere = false

    if let audioView = self.view.subviews.filter (
        { $0.tag == 123456}).first  {

        audioView.tag = 123456
        isAlreadyThere = true
    }

    if isAlreadyThere {
        return
    }

    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.light)
    let backView = UIVisualEffectView(effect: blurEffect)
    backView.tag = 123456
    backView.frame = CGRect(x: 0, y: self.view.frame.height+35 , width: self.view.frame.width, height: 40)
    backView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    view.addSubview(backView)

    pauseButton = UIButton(type: .custom)
    pauseButton.titleLabel?.font = Util.getFontSize()
    pauseButton.setTitle("Pause", for: .normal)
    pauseButton.setTitleColor(UIColor.black, for: .normal)
    pauseButton.addTarget(self, action: #selector(pausePressed(_:)), for: .touchDown)

    durationLabel = UILabel()
    durationLabel.textColor = UIColor.black
    durationLabel.font = Util.getFontSize()
    durationLabel.textAlignment = .center
    durationLabel.text = "0:00"

    stopButton = UIButton(type: .custom)
    stopButton.titleLabel?.font = Util.getFontSize()
    stopButton.setTitle("Stop", for: .normal)
    stopButton.setTitleColor(UIColor.black, for: .normal)
    stopButton.addTarget(self, action: #selector(stopPressed(_:)), for: .touchDown)

    let stackView = UIStackView(frame: CGRect(x: 0, y:0 , width: backView.frame.width, height: 40))
    stackView.alignment = .fill
    stackView.axis = .horizontal
    stackView.distribution = .fillEqually
    stackView.spacing = 5
    stackView.addArrangedSubview(pauseButton)
    stackView.addArrangedSubview(durationLabel)
    stackView.addArrangedSubview(stopButton)

    backView.addSubview(stackView)

    if audioViewYposition == nil {
        audioViewYposition = self.view.frame.height - 40
    }

    UIView.animate(withDuration: 0.2, delay: 0.1, options: .curveEaseInOut, animations: {
        backView.frame.origin.y = self.audioViewYposition
    }, completion: nil)

Answer 1

如错误所述，您需要在内容视图上添加子视图，而不是直接在视觉效果视图上，因此解决方案是：

backView.contentView.addSubview(stackView)

确保您的异常断点已启用以从断点跳过几帧以在控制台中查看错误消息：

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', 
reason: '<UIStackView: 0x109946ff0; frame = (0 0; 375 40); layer = <CATransformLayer: 0x1c4236640>> 
has been added as a subview to 
<UIVisualEffectView: 0x109945f40; frame = (0 702; 375 40); autoresize = W+H; tag = 123456; layer = <CALayer: 0x1c002ebc0>>. 
Do not add subviews directly to the visual effect view itself, 
instead add them to the -contentView.'