UIPageViewController show view following device size. how to force it to fix?

Question

I implemented 3 container view which will be fill with page view like photo below

but when I install it in iphone the last one in the below following the size of the device so it become smaller. why is that like that? I tried to make a width to make it fix but still nothing change. is anyone know how to do this? Thank you for the answer

this is in the app

Answer 1

found the solution by adding this line of code in my view controller that used as an image in UIPageViewController

self.view.translatesAutoresizingMaskIntoConstraints = false;