iOS Autolayout - Frame size not set in viewDidLayoutSubviews

Question

I\'m working on a keyboard for iOS 8 using Autolayout to place the buttons on the view.
When I\'m changing the layout using constraints, everything is appearing correctl

Answer 1

Yes! I solved that problem myself.

I'm not sure if I got it right, but that's what I think:

• viewDidLayoutSubviews get's called every time when the layout is changing
• viewDidLayoutSubviews get's called when the direct subviews of my view did layout, but the subviews of that subviews did not layout at that moment, so you can't get the size of them.

My solution now was to manually call .layoutSubviews() on all my views which contains all my buttons of my keyboard. After that, I get the size of all the buttons I want.

Please correct me if I'm wrong.

Answer 2

I encountered a very similar issue (upvoted question) and found beeef's answer to point in the right direction. Given that Apple's documentation says not to call layoutSubviews() directly, I instead did as follows (where mySubView is a direct subview of self.view):

override func viewDidLayoutSubviews() {
    // self.view's direct subviews are laid out.
    // force my subview to layout its subviews:
    self.mySubView.setNeedsLayout()
    self.mySubView.layoutIfNeeded()

    // here we can get the frame of subviews of mySubView
    // and do useful things with that...
}

Just FYI, in my case mySubView is a UIScrollView, and I need to get the frame of one of its subviews, such that I can set the contentOffset accordingly before the view appears. I'm not sure whether viewDidLayoutSubviews() is the best place to do this, but it ensures that mySubView has been laid out.