Centering subview's X in autolayout throws “not prepared for the constraint”

Question

I have a custom UIView subclass which is being initialized via a nib.

In -awakeFromNib, I\'m creating a subview and attempting to center it in its super

Answer 1

Additional Tips:

I have a newly developed App which running fine on iOS7 but get error on iOS8 "The view hierarchy is not prepared for the constraint".

Read some other post said that the (sub)views need to be added before create constraints. I did that but still got the error.

Then I figured out that I should create constraints under -(void)viewDidAppear instead of viewDidLoad