UICollectionViewCell的大小适合设备旋转时的所有单元格

Question

我有一个寻呼机全屏collectionview。设备旋转时，collectionview的第一个单元格适合横向和纵向模式下的collectionview。但是，当我在collectionview上滚动下一个单元格时，它显示了两个单元格。而且它不适合所有屏幕。滚动collectionview并旋转时，如何使所有单元格大小适合collectionview。我尝试了invalideLayout（）并尝试了许多方法。但是我无法达到。我只想要，尽管滚动和旋转，collectionviewcell在任何情况下都可以安装到整个屏幕上。

P.S collectionviewcell的大小应为整个屏幕的大小。

public override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {
    if UIDevice.current.orientation.isLandscape,
        let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
        let width = view.frame.height
        layout.itemSize = CGSize(width: width, height: UIScreen.main.bounds.width)
        layout.invalidateLayout()
    } else if UIDevice.current.orientation.isPortrait,
        let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
        let width = view.frame.width
        layout.itemSize = CGSize(width: width , height:  UIScreen.main.bounds.height)
        layout.invalidateLayout()
    }
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    let width = view.frame.size.width
    return CGSize(width: width , height: UIScreen.main.bounds.height)
}

Answer 1

请确保如下所述消除单元格之间的间距。这样可以解决您的问题。

Answer 2

您必须在viewWillLayoutSubviews（）中编写代码。像这样

覆盖func viewWillLayoutSubviews（）{         super.viewWillLayoutSubviews（）

    guard let flowLayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout else {
        return
    }



    if UIDevice.current.orientation == .landscapeLeft
    {
        flowLayout.itemSize = CGSize(width: self.view.frame.width, height: 500)
    }
    else if UIDevice.current.orientation == .landscapeRight
    {
        flowLayout.itemSize = CGSize(width: self.view.frame.width, height: 500)
    }

    flowLayout.invalidateLayout()
}

Answer 3

您可以尝试采用以下方法吗？

第一种方法

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {

   super.viewWillTransition(to: size, with: coordinator)

   // YOUR CODE OR FUNCTIONS CALL HERE

}

第二种方法

override func viewDidLoad() {
    super.viewDidLoad()        

    NotificationCenter.default.addObserver(self, selector: #selector(ViewController.rotated), name: NSNotification.Name.UIDeviceOrientationDidChange, object: nil)
}

deinit {
     NotificationCenter.default.removeObserver(self)
}

func rotated() {
    if UIDevice.current.orientation.isLandscape,
        let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
        let width = view.frame.height
        layout.itemSize = CGSize(width: width, height: UIScreen.main.bounds.width)
        layout.invalidateLayout()
    } else if UIDevice.current.orientation.isPortrait,
        let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
        let width = view.frame.width
        layout.itemSize = CGSize(width: width , height:  UIScreen.main.bounds.height)
        layout.invalidateLayout()
    }
}