UIScreen.main 、 super.view 和其他视图的中心不在屏幕中间

Question

我的目标是在 iPhone 屏幕的中央放置一个按钮，使按钮与屏幕边缘的距离相等。我尝试以两种方式添加此按钮，方法是为框架指定一个以父视图 super.view 或 UIScreen.main 为中心的原点。我也尝试过使用约束将按钮的中心重新设置为父视图的中心。在这两种情况下，按钮看起来都靠近屏幕中心，但不是直接居中。需要注意的是，我使用的是 ARSCNView，其次我没有使用 .xib 或故事板来配置 UI。您可以查看相机按钮的屏幕截图（红色）： camera button not centered.

您可以在此处查看视图控制器中我当前代码的样子：（我已经注释掉了定义屏幕中心的各种方式）

let sceneView = ARSCNView()

func addCameraButton(){
   //let cameraCenter = CGPoint(x:super.view.center.x, y: super.view.center.y)
   //let cameraCenter = CGPoint(x:UIScreen.main.bounds.midX, y: UIScreen.main.bounds.midY)
    let cameraCenter = CGPoint(x:sceneView.center.x, y:sceneView.center.y)
    let cameraSize = CGSize(width: 100, height: 100)
    let cameraRect = CGRect(origin: cameraCenter, size: cameraSize)
    cameraButton = KYShutterButton(frame:cameraRect, shutterType: .normal, buttonColor: UIColor.gray)
    cameraButton?.addTarget(self, action: #selector(cameraSnap), for: .touchUpInside)
    self.view.addSubview(cameraButton!)

    let verticalCenterCamera = NSLayoutConstraint(item: cameraButton, attribute: .centerY, relatedBy: .equal, toItem: self.view, attribute: .centerY, multiplier: 1.0, constant: 0.0)

    let horizontalCenterCamera = NSLayoutConstraint(item: cameraButton, attribute: .centerX, relatedBy: .equal, toItem: self.view, attribute: .centerX, multiplier: 1.0, constant: 0.0)

    NSLayoutConstraint.activate([verticalCenterCamera, horizontalCenterCamera])
    cameraButton?.layoutIfNeeded()

Answer 1

使用自动布局时，您需要在以编程方式设置约束时将 translateAutoresizingMaskIntoconstarints 设置为 false

cameraButton?.translateAutoresizingMaskIntoconstarints = false
let verticalCenterCamera = NSLayoutConstraint(item: cameraButton, attribute: .centerY, relatedBy: .equal, toItem: self.view, attribute: .centerY, multiplier: 1.0, constant: 0.0)
let horizontalCenterCamera = NSLayoutConstraint(item: cameraButton, attribute: .centerX, relatedBy: .equal, toItem: self.view, attribute: .centerX, multiplier: 1.0, constant: 0.0)
NSLayoutConstraint.activate([verticalCenterCamera, horizontalCenterCamera])
self.view.layoutIfNeeded()

//

有框架布局

self.view.addSubview(cameraButton!)
self.cameraButton?.center = self.sceneView.center

UIScreen.main 、 super.view 和其他视图的中心不在屏幕中间

Center for UIScreen.main , super.view and other views are not centered in middle of screen

uikit

ios

cgrect

swift

arkit