why some space left on header and footer portion of iPhone 4-inch simulator. its running fine on normal iPhone screen.i just developed app on Xcode 4.3 but after upgrading to 4.5 there one option to change simulator retina to 4 inch screen and its left some space automatically on header and footer which i focus by red box in below image.

You’ll see that you have a warning about the Default-568h@2x.png file, the retina display splash. Add it and if the screen was designed properly it should fill the black gaps.