Why viewDidLayoutSubviews is called twice only on first run?

Question

It's driving me crazy this. Only on first run the viewDidLayoutSubviews is called twice.

Here is the code I'm using:

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()
    }

}

And in my ViewController I call this :

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
    }


}

score 4 · Answer 1 · edited Aug 09 '17 at 06:37

4

There is no guarantee as for how many times viewDidLayoutSubviews will be called.

You can find a great discussion in this Stack Overflow post:
When is layoutSubviews called?

edited Aug 09 '17 at 06:37

Pang

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answered May 14 '16 at 14:15

maddy

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score 2 · Answer 2 · edited Aug 09 '17 at 07:14

I found this article useful. A summary from what it says:

init does not cause layoutSubviews to be called (duh)

addSubview causes layoutSubviews to be called on the view being added, the view it’s being added to (target view), and all the subviews of the target view

setFrame intelligently calls layoutSubviews on the view having it’s frame set only if the size parameter of the frame is different

scrolling a UIScrollView causes layoutSubviews to be called on the scrollView, and it’s superview

rotating a device only calls layoutSubview on the parent view (the responding viewControllers primary view)

removeFromSuperview – layoutSubviews is called on superview only (not show in table)

Why viewDidLayoutSubviews is called twice only on first run?

2 Answers2