getting highly confused by odd behaviour of viewController Method - ios

Question

I have overrided a method as
override func viewDidLayoutSubviews() {
// creating bottom line for textField
let border = CALayer()
let width = CGFloat(1.0)
border.borderColor = UIColor.whiteColor().CGColor
border.frame = CGRect(x: 0, y: emailTextField.frame.size.height - width, width: emailTextField.frame.size.width, height: emailTextField.frame.size.height)
border.borderWidth = width
emailTextField.layer.addSublayer(border)
emailTextField.layer.masksToBounds = true
}
Now whats happening is that when I run my app on Iphone 6, 6+ every thing works fine. But when I run the same code on iphone5 (Simulator + real Device ) viewDidLayoutSubViews is getting called infinite times and my app becoms unresponsive. I solved the problem by using a bool variable. But I do not understand why is this happening. So can someone please explain this to me.
Thanks :-)

Answer 1

As docs says that viewDidLayoutSubviews method need for change layout
Called to notify the view controller that its view has just laid out
its subviews. When the bounds change for a view controller's view,
the view adjusts the positions of its subviews and then the system
calls this method. However, this method being called does not indicate
that the individual layouts of the view's subviews have been
adjusted. Each subview is responsible for adjusting its own layout.
Move your code to viewDidLoad method or to loadView if you are not using xibs or Storyboards
override func viewDidLoad() {
// creating bottom line for textField
let border = CALayer()
let width = CGFloat(1.0)
border.borderColor = UIColor.whiteColor().CGColor
border.frame = CGRect(x: 0, y: emailTextField.frame.size.height - width, width: emailTextField.frame.size.width, height: emailTextField.frame.size.height)
border.borderWidth = width
emailTextField.layer.addSublayer(border)
emailTextField.layer.masksToBounds = true
}
If you would like to change border.frame you can set it to class variable and change it in viewDidLayoutSubviews method
override func viewDidLayoutSubviews() {
self.border.frame = CGRect(x: 0, y: emailTextField.frame.size.height - width, width: emailTextField.frame.size.width, height: emailTextField.frame.size.height)
self.border.borderWidth = width
}

Answer 2

Just replace
emailTextField.layer.addSublayer(border)
with this:
emailTextField.addSublayer(border)
-> you want to add sublayer to a view - as you want to apply masksToBounds property to it either.

Answer 3

Move your implementation inside viewDidLayoutSubviews. I got the same issue. Hope it will work.
override func viewDidLayoutSubviews()
{
//Your CODE
}