ios - 无法捕获 iOS 上从 "upsidedown"到横向的方向变化

Question

当屏幕方向改变时，我需要使我的 Collection View 布局无效。由于 iPhone X 和其他设备都有安全区域插入；我需要根据屏幕安全区域插图定位单元格的 subview 。

如果您在纵向和左右横向之间切换，则没有问题。但如果你从颠倒切换，我无法捕捉到方向变化，并且自动无法

我尝试了两种现有的方法。

首先是使用NotificationCenter。其次是重写 viewWillTransitionToSize:withTransitionCoordinator: 函数。都是一样的。

在 CollectionViewController 中:

    NotificationCenter.default.addObserver(forName: UIDevice.orientationDidChangeNotification, object: nil, queue: nil) { (notif) in
      self.collectionViewLayout.invalidateLayout()
    }

在单元格中:

  override func layoutSubviews() {
    super.layoutSubviews()

    let orientation = UIDevice.current.orientation
    if let insets = UIApplication.shared.keyWindow?.safeAreaInsets {
      if orientation == .landscapeLeft {
        titleLabelLeadingConstraint.constant = insets.left + 20
        titleLabelTrailingConstraint.constant = 20
      } else if orientation == .landscapeRight {
        titleLabelLeadingConstraint.constant = 20
        titleLabelTrailingConstraint.constant = insets.right + 20
      } else {
        titleLabelLeadingConstraint.constant = 20
        titleLabelTrailingConstraint.constant = 20
      }
    }

    print("orin: \(orientation.rawValue) | left: \(titleLabelLeadingConstraint.constant) | right: \(titleLabelTrailingConstraint.constant)")

  }

当您从倒置状态切换到倒置状态时，不会调用 print() 函数。但是collectionviewlayout的invalidateLayout()函数正在被调用。

Answer 1

正如您已经尝试过的那样，您可以使用 viewWillTransitionToSize:withTransitionCoordinator: 检测方向变化。

我不知道你的第一次尝试，但是，尝试一下:

      override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
         //If you need to invalidate your collectionView layout, do it in this function
         super.viewWillTransition(to: size, with: coordinator)
         if UIDevice.current.orientation.isLandscape {
          //
         } else {
           //
         }
      }

如果您需要知道landscapeLeft 或Right 之间的区别，请按以下方式尝试您的代码:

      override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
         //If you need to invalidate your collectionView layout, do it in this function
    super.viewWillTransition(to: size, with: coordinator)

     if let insets = UIApplication.shared.keyWindow?.safeAreaInsets {
        if UIDevice.current.orientation == .landscapeLeft {

        titleLabelLeadingConstraint.constant = insets.left + 20
        titleLabelTrailingConstraint.constant = 20

      } else if UIDevice.current.orientation == .landscapeRight {

        titleLabelLeadingConstraint.constant = 20
        titleLabelTrailingConstraint.constant = insets.right + 20

      } else {

        titleLabelLeadingConstraint.constant = 20
        titleLabelTrailingConstraint.constant = 20

      }
    }
  }

NOTE: You don't need to register an observer