I have uploaded a game targeted for iPhone devices only and it was rejected due to:
Your app was not optimized to support the device screen size or resolution.
Looking at the attached screenshot provided by the reviewers there was indeed a problem with how the UI elements were laid out.
Of course before I uploaded the binary I tested it on real devices (iphone4s/5/5s/6/6+) with no problems and everything looked as expected.
Then I ran it on an iPad simulator and got the same result Apple reviewers got (the entire game scene is zoomed and the layout is different and cropped incorrectly).
The strange thing is that if I close the app and run it again (in the simulator) everything works as expected!.
The game is using SpriteKit but It looks like a problem with the simulator rather than with the game itself as it works as expected on each iPhone device. (again it happens only on the first launch). I do not have a real iPad device but I already released 4 iPhone targeted apps with no problem with iPad devices (and without making specific changes for supporting iPad devices)
My question is if someone else encountered this problem with an app targeted for iPhone devices only?