CODEWITHSUNDEEP
iosipadios5uiviewcontrolleruipageviewcontroller
Gytis
Gytis

Reputation: 670

Why is the UIPageViewController resizing its UIViewControllers views after the page turn?

Within the pageViewController:viewControllerAfterViewController: method, just before the return statement, the view which is about to be returned as the next page has the correct view frame size.

However immediately after the pageViewController:didFinishAnimating:previousViewControllers:transitionCompleted: method is called, I check the frame size of the newly introduced view controller ([pageViewController2.viewControllers objectAtIndex:0];) and I find it resized.

Note that, I have set [self.pageViewController.view setAutoresizesSubviews:NO] and the autoresizing mask to None for the newly created ViewController.

Any ideas in which step the new ViewController is being resized?

Upvotes: 3

Views: 2466

Answers (1)

Theo Bendixson
Theo Bendixson

Reputation: 601

I think the problem is inherently related to the nature of UIPageViewController. It is built from UIScrollView. I don't exactly know why there is strange resizing behavior, but it seems to be particularly pronounced when the view controllers that make up your pages use auto layout. Seemingly, locking the constraints in your page view controllers to the superview makes the elements resize after the transition because the superview is itself getting resized after said transition.

This sucks because Apple is basically pushing all of us to adopt auto layout. Auto layout is awesome, and I recommend everyone use it from now on, but it really really sucks when you use it with a UIPageViewController. They really ought to either scrap that class or build something easier for developers, something that can be dragged into a storyboard outright.

A few things to consider.

1.) Don't lock anything to the "Top Layout Guide" or the "Bottom Layout Guide". Also make sure you have "Constrain To Margins" disabled on any view intended to hug the sides of the screen.

2.) If you are using a label in your individual page / content view controllers, make sure you bind/constrain it to something other than the superview. I wanted to place a label over a UIImageView, so I aligned the label to the leading and top edges of the image view (using AutoLayout constraints only), creating an offset to give the label some margins.

3.) The following would otherwise be a good tutorial. However, it is a bit outdated. I downloaded the project and basically modified it to get a UIPageViewController implementation that works. The only problem with this project is that it doesn't use AutoLayout. I'm currently writing a blog post that more clearly discusses how to use UIPageViewController and Autolayout together.

http://www.appcoda.com/uipageviewcontroller-storyboard-tutorial/

Upvotes: 5

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