当设备方向更改 SWIFT 5 时重绘自定义 UIVIEW

Question

我为新的 UIVIEW 编写了代码，但是在设备旋转后，UIVIEW 的绘制没有被清理以适应新的情况！并保持对用户可见！看图片。我们如何解决这个问题？

导入 UIKit

class ViewController: UIViewController
{
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
    }
    

    override func viewDidLayoutSubviews()
    {

        var drawView = UIView()

        let drawViewOffsetFromTop = max( 25 , Int( view.safeAreaInsets.top ) )
        let drawViewOffsetFromBottom = max( 25 , Int( view.safeAreaInsets.bottom ) )
        
        let drawViewWidth = Int( view.frame.size.width ) - 2*25
        let drawViewHeight = Int( view.frame.size.height) - drawViewOffsetFromTop - drawViewOffsetFromBottom

        drawView = UIView(frame: CGRect(x: 25 , y: drawViewOffsetFromTop, width: drawViewWidth  , height: drawViewHeight ))
        drawView.backgroundColor = UIColor.gray
        drawView.layer.cornerRadius = 15
        view.addSubview(drawView)
   
    }
    
    
}

Answer 1

您可以使用 Autolayout 让事情变得简单。
完全移除覆盖viewDidLayoutSubviews。

在viewDidLoad中使用以下内容

override func viewDidLoad()
{
    super.viewDidLoad()
    var drawView = UIView()

    //Setup Constraints for `drawView`
    drawView.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        drawView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 25),
        drawView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -25),
        drawView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 15),
        drawView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -15)
    ])

}

编辑：没有自动布局的解决方案
问题是您的 drawView 在视图层次结构中被多次添加！您可以只添加一次，然后只更改框架。

class ViewController: UIViewController {
        
    var drawView = UIView()

    override func viewDidLoad()
    {
        super.viewDidLoad()
        view.addSubview(drawView)
        drawView.backgroundColor = UIColor.gray
        drawView.layer.cornerRadius = 15
    }


    override func viewDidLayoutSubviews()
    {


        let drawViewOffsetFromTop = max( 25 , Int( view.safeAreaInsets.top ) )
        let drawViewOffsetFromBottom = max( 25 , Int( view.safeAreaInsets.bottom ) )
        
        let drawViewWidth = Int( view.frame.size.width ) - 2*25
        let drawViewHeight = Int( view.frame.size.height) - drawViewOffsetFromTop - drawViewOffsetFromBottom
        
        drawView.frame = CGRect(x: 25 , y: drawViewOffsetFromTop, width: drawViewWidth  , height: drawViewHeight )

    }
}

Answer 2

首先，您应该不要将创建 UIView 的代码放在viewDidLayoutSubviews 中，而是在viewDidLoad 中创建并添加它。您可以将视图框架更新代码放入viewDidLayoutSubviews。

问题是您多次添加drawView 而没有删除现有的。此外，您不必要地在不同的行中多次初始化 drawView。

要解决此问题，请在您的控制器中创建drawView，将其添加到viewDidLoad 中的superview 并编辑您的viewDidLayoutSubviews，如下所示：

class ViewController: UIViewController {
    private var drawView : UIView = UIView()

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(drawView)
    }    
    
    override func viewDidLayoutSubviews() {
        let drawViewOffsetFromTop = max(25 , Int(view.safeAreaInsets.top))
        let drawViewOffsetFromBottom = max(25 , Int(view.safeAreaInsets.bottom))
        
        let drawViewWidth = Int(view.frame.size.width ) - 2*25
        let drawViewHeight = Int(view.frame.size.height) - drawViewOffsetFromTop - drawViewOffsetFromBottom

        drawView.frame = CGRect(x: 25, y: drawViewOffsetFromTop, width: drawViewWidth, height: drawViewHeight)
        drawView.backgroundColor = UIColor.gray
        drawView.layer.cornerRadius = 15
    }
}

Answer 3

//▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
var drawView = UIView()
//▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼


//█ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █
override func viewDidLoad()
{
    super.viewDidLoad()
    view.backgroundColor = UIColor.gray
}
//█ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █



//█ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █ █
override func viewDidLayoutSubviews()
{

    //▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
    let backView = UIView(frame: CGRect(x: 0 , y: 0, width: view.frame.size.width  , height: view.frame.size.height ))
    backView.backgroundColor = UIColor.gray
    view.addSubview(backView)
    //▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼


    //▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
    let drawViewOffsetFromTop = max( 25 , Int( view.safeAreaInsets.top ) )
    let drawViewOffsetFromBottom = max( 25 , Int( view.safeAreaInsets.bottom ) )
    let drawViewOffsetFromRight = max( 25 , Int( view.safeAreaInsets.right ) )
    let drawViewOffsetFromLeft = max( 25 , Int( view.safeAreaInsets.left ) )
    //▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
    

    //▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
    let drawViewWidth = Int( view.frame.size.width ) - drawViewOffsetFromRight - drawViewOffsetFromLeft
    let drawViewHeight =  Int( view.frame.size.height) - drawViewOffsetFromTop - drawViewOffsetFromBottom
    //▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
    
    //▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
    drawView = UIView(frame: CGRect(x: drawViewOffsetFromRight , y: drawViewOffsetFromTop, width: drawViewWidth  , height: drawViewHeight ))
    //▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼

    
    //▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
    drawView.backgroundColor = UIColor.systemTeal
    drawView.layer.cornerRadius = 12
    drawView.layer.borderWidth = 5
    drawView.layer.borderColor = UIColor.black.cgColor
    view.addSubview(drawView)
    //▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼

    

    

}
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