Question

这让我很疯狂。只有在第一次运行时才会调用viewDidLayoutSubviews两次。

以下是我正在使用的代码：

class CICViewController: UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
    }



    func addQLabel(qLabel: UILabel, questionString: String, bgrLabel: UILabel) {// some code goes here
    }

    func makeRoundQButtons(qButtons:[UIButton]) {
      // some code goes here

    }

    func addArrows(numberOfArrows:Int, buttonCurAngle:Double) {//some code goes here
    }

    func animateButtons(qButtons:[UIButton], buttonCurAngle:Double) {

     // some code goes here

    }



    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)

    }

    func backTapped(sender: UIBarButtonItem) {
        navigationController?.popViewControllerAnimated(false)
       //some code goes here

    }

    func restartTapped(sender: UIBarButtonItem) {
        navigationController?.popToRootViewControllerAnimated(false)
        //some code goes here
    }


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

}

在我的ViewController中，我称之为：

class OneViewController: CICViewController {

  override func viewDidLoad() {
        super.viewDidLoad()

 //some code goes here
}


    override func viewDidLayoutSubviews() {

        super.viewDidLayoutSubviews()
        print("viewDidLayoutSubviews")
        self.makeRoundQButtons(qButtons)
        self.animateButtons(qButtons, buttonCurAngle: 2.0)

    }

    override func viewDidAppear(animated: Bool) {
     //nothing goes here
    }


}

Answer 1

无法保证调用viewDidLayoutSubviews的次数。

您可以在此Stack Overflow帖子中找到一个很好的讨论：
When is layoutSubviews called?

Answer 2

我发现this article很有用。它的内容摘要如下：

init不会导致layoutSubviews被调用（duh）

addSubview导致在添加的视图，要添加到的视图（目标视图）以及目标视图的所有子视图中调用layoutSubviews
  只有当框架的尺寸参数不同时，
setFrame智能地调用layoutSubviews视图上的UIScrollView

滚动layoutSubviews会导致在scrollView上调用layoutSubview，这是超级视图

旋转设备仅在父视图（响应viewControllers主视图）上调用removeFromSuperview

layoutSubviews - 仅在超级视图中调用{{1}}（未在表格中显示）

为什么viewDidLayoutSubviews仅在首次运行时被调用两次？

2 个答案: