iphone app size smaller than screen

I'm developing an app and have come against a strange issue I can't find the answer for - when testing the app on an iPhone 5 the whole app display window is shrunk down to what looks like a 3.5 size display (the top and bottom of the screen are black and even the status bar is pushed down). When I test the app on an iPhone 5s running iOS 8 it displays full screen as expected.

Also when testing in the iOS simulator for iphone 5, and 5s it displays as expected. I'm using xcode 6 for development.

Any help would be greatly appreciated.

How do I get my iPhone apps back to normal size?

How to Zoom out to Normal Size on iPhone. To restore icons to normal size, hold three fingers together and double-tap the screen with all three fingers at once. This gesture returns the Zoom level to normal.

You need to set splash screen for your app. Otherwise it will take 3.5 screen size. Just set the splash screen and you will be done.