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iosobjective-cautolayoutlayoutsubviews

Issue while using viewDidLayoutSubviews

I have heard that viewDidLayoutSubviews is the best place to alter the layout when we have used constraints.

So I jumped to viewDidLayoutSubviews

I have created three UIViews and SubViewed them on SuperView. I am not mentioning the code for frame calculation.

 [self.view addSubview:imgMiddleCircle];
 [self.view addSubview:imgFirstCircle];
 [self.view addSubview:imgLastCircle];

Using this piece of I am adding these circles.

Now when I run my code In viewDidLayoutSubviews I get following screens:

enter image description here

And when I switch to viewWillLayoutSubviews I am getting this on screen:

enter image description here

Why I am getting extra two circles in viewDidLayoutSubviews even I am creating three circles.

And why in viewWillLayout gives the correct Output.

Solution

  • You should code for the fact that viewDidLayoutSubviews is called multiple types.

    Ideally addSubview: should be happening in a place like viewDidLoad where you are sure it is only called once.

    You can create a flag to avoid calling addSubview: multiples types (not my personal choice)

    Otherwise, try to move your set up code to viewDidLoad and force the view to render itself before doing your calculation:

    [yourView setNeedsLayout];

    [yourView layoutIfNeeded];