topLayoutGuide and custom transistions in iOS 7

Yesterday the iOS 7 update for Taskboard was released. I remember when I was designing the first version back in October or November of 2011. I wanted the cards and boards to be the focus and tried to do away with the opaque top toolbar. I couldn't find a color for that toolbar that worked with the variety of background colors you could choose within the app. In the end I settled on a black color similar to the one in my Meetings app. Now, in iOS 7, the translucent navigation bar works perfectly, taking on the hue of the selected background.

Working on updates - overcoming the initial hurdles of removing deprecated API, updating icons, artwork - motivates me. I've been looking over the list of suggestions customers have given me.

Though that update is out, I'm following it with another. I'm making use of the custom transistion animations in iOS 7 and ran into an issue that I'm simply documenting here. I use AutoLayout to make sure the top of the boards are positioned a certain distance from the topLayoutGuide. The length of the topLayoutGuide is 64 when I check it from within viewDidLayoutSubviews, as expected (20pt status + 44pt nav bar). If I push a new view controller using the standard push animation (ie, no transitioningDelegate is set) and then press the back button, the topLayoutGuide remains 64.

If I use my custom transistion, however, the topLayoutGuide becomes 20 once I pop the pushed view. The visual result is that the boards are shifted up under the navigation bar.

I found a post on StackOverflow that seems to suggest the same thing may be happening with the UIPageViewController. I've also confirmed the issue (ie, top guide differing after push-then-pop) in a couple of the well-done transistion demo projects out there, such as SOLPresentingFun.

My solution, for now, is to change my AutoLayout constraints so that I don't rely on the topLayoutGuide. I may not understand how this works well enough, or it might be an iOS 7 bug.