camera view - can settings disrupt button response on a camera view on iPhone 5S?

Question

I have a strange situation...

I implemented an in-app camera based on Apple's AVCam sample. It works just fine. My question is not about the actual camera implementation, but rather... What could cause a view's buttons to work on one iPhone 5S but fail on another iPhone 5S. Both are using the same build of the app, they have the same iOS version installed (7.0.4), etc.

The problem is...the camera starts and the camera preview displays just fine, but the buttons on that view (i.e. the shutter release, flash options, front/back camera switch, etc) all fail to respond. His iPhone 5S is the only one out of 4 iPhone 5S's that has the problem.

Trying to narrow down what can be different until I can hook the "sad" iPhone 5S up to my debugger in a few days when I see my client again (it's his)... we did notice that my phone asked for permission to access my photos and his did not...

Is there perhaps some system setting that he could have enabled that would cause this check to be skipped? I ask because I wonder if the camera scene's view controller is waiting for something from that check and therefor hanging the UI.

Any ideas would be appreciated

Answer 1

Finally tracked down the issue...

The difference was that on my developer phone, I had a few hundred to 1000 pictures in my camera roll. On my client's phone, he had about 6,000 pictures, so obviously getting those takes longer. If we were patient, the view eventually did come back alive after the enumeration block finished.

Also, I was asking my UICollectionView to scroll to the end (where the newest photos are) after it had finished loading all the camera roll images into itself. With few photos, the timing was fine, but with lots of photos, the timing was off and it was trying to scroll before it had finished enumerating. The solution, since there is no callback for "didFinishReloadingData" was no call the scroll method using -performSelector:withObject:withDelay to ensure that it gets called AFTER the enumeration block and reloadData are finished.