#uipresentationcontroller

[invasivecode]

Custom View Controller Transitions and Storyboard

A few weeks ago, I wrote this post about the storyboard's features introduced in iOS 9. In that post, I mentioned that you can now trigger a custom view controller transition through storyboard segues. Starting from iOS 9, you can perform view controller transitions using the new APIs introduced by Apple first in iOS 7 and, then slightly modified in iOS 8. These APIs use dedicated objects to control the transition animations. In this post, I am going to show you how to use these APIs and trigger these animations from the storyboard.

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[cocoa]

How can I use both UIPopoverPresentationController and custom “adaptive” presentation logic?

In Tumblr for iOS, we have a view controller that gets presented differently on iPhone and on iPad:

iPhone: Modally, as the child of a custom container view controller, presented with a custom animation controller

iPad: In a popover

I'm in the process of trying to implement this same behavior using the new UIPresentationController classes introduced in iOS 8, and seem to have already hit an unfortunate limitation.

It's easy to get the popover showing up correctly on iPad, with just the following code:

presentedController.modalPresentationStyle = UIModalPresentationPopover; presentedController.popoverPresentationController.permittedArrowDirections = UIPopoverArrowDirectionUp; presentedController.popoverPresentationController.sourceRect = button.bounds; presentedController.popoverPresentationController.sourceView = button; presentedController.popoverPresentationController.delegate = self; [self presentViewController:presentedController animated:YES completion:nil];

On iPhone, this same controller will be presented modally, but first we need to wrap it in a custom container view controller. To do this, we implement a couple of methods on the UIPopoverPresentationControllerDelegate protocol:

- (UIModalPresentationStyle)adaptivePresentationStyleForPresentationController:(UIPresentationController *)controller { return UIModalPresentationOverFullScreen; } - (UIViewController *)presentationController:(UIPresentationController *)presentationController viewControllerForAdaptivePresentationStyle:(UIModalPresentationStyle)style { return [[CustomContainerController alloc] initWithRootViewController:presentationController.presentedViewController]; }

Simple enough so far.

A “dimming view” is faded in as the view controller transitions on screen. The end result looks something like this:

The custom container controller is animated on screen using a custom animation controller conforming to UIViewControllerAnimatedTransitioning. In iOS 7, this animation controller was also responsible for showing the dimming view.

As of iOS 8, adding the dimming view to the view hierarchy and modifying its opacity should no longer be the responsibility of the animation controller. Instead, a custom UIPresentationController subclass should take care of this. The same UIViewControllerTransitioningDelegate that vends our custom animation controller can also vend a custom presentation controller, providing for a cleaner separation of concerns.

Here's the problem I'm facing: my UIViewControllerTransitioningDelegate is never asked for a custom presentation controller, presumably because it already has one – the UIPopoverPresentationController that we started with. As such, I seemingly can't break the ”presentation” out of my custom animation controller, the way that Apple suggests we should.

Am I missing something, or are UIPopoverPresentationController and custom presentation controller behavior really mutually exclusive?