Steps to reproduce:
I've encountered the same issue. It seems that LaunchScreen.xib can't adapt to the screen size of all 4-inch devices under iOS7.
I was able to resolve the issue manually, seems like it is a bug with Xcode for now and I will file a radar report.
To resolve the issue, follow the below steps:
This should fix the issue.
I encountered the same problem some days ago and I founded out that the problem in my case was the missing LaunchScreen.xib in General setting under App icons and launch images:
I had the same issue with Xcode 7 beta 1 and the UICatalog sample code and could resolve it by choosing Main.storyboard in General Settings under App Icons and Launch Images for the Launch Screen File.
On iOS7 (which I was testing on) if I did not add the 640x1136 image in the LaunchImage assets for iPhone Portrait 7.0 Retina I would get the top and bottom bar. Adding the asset in PNG format resolved the issue on iOS7.