Background:
I have a custom container controller, which just like UITabBarController, but with switch animation. And I use auto layout to achieve.
Because switch between child controllers is dynamic, the proper constraints are added to child view controller when its's view is added into container's view, not pre-setup in IB. (The constraints are added to the superview of course)
http://d.pr/i/q6NF Container Controller Nib Setup
PS:
The detail of constraints
H:|[Child](Change the constraint's constant to animation from left/right to right/left)
H:[Child(==Super)]
V:|[Child]|
Where is the Problem:
One of the child controller is a navigation controller, things go wrong when the navigation controller present a modal view controller (using presentViewController:animated:completion:), and dismiss it(usingdismissViewControllerAnimated:completion:), after present/ dismiss the frame of navigation controller become (x, y, 0, 0), It seems like the auto layout becomes invalid, maybe the constraints been removed.
http://d.pr/i/VmvL The Present/ Dismiss Process
Research
I haven't use code to verify what happen to these constraints yet, but with Spark Inspector I see the views presentation change during the present/ dismiss process. When My navigation controller present a modal view controller, iOS just swap the whole navigation controller's view to the modal view controller's view. And when navigation controller's view come back, the auto layout doesn't work anymore.
Possible Solution
One of the solution I came up with is let my container controller present modal controller.
Or I just change my container controller to no auto layout.
The fact is ever since I start using auto layout, the problems this