I have a bit of a problem, for which I can't find a solution. I have a view controller, which we'll call Bob. Bob is launched via a push segue from another view controller. Bob used to appear on the device, but then I changed the "collectionView:cellForItemAtIndexPath:" method and did a rebuild - at some point after that, Bob started appearing only in my view debugger. I've verified that viewWillAppear gets called, but neither viewDidAppear nor collectionView:cellForItemAtIndexPath do. Interestingly, my CPU stat sits at around 100%. Solution: Pause the app with the debugger to check if the app is in a loop.