This code initialize the different sizes of the iPhone/iPad screens to do something depending on which device we are using.

gistfile1.m

UIDevice *device = [[UIDevice alloc] init];

if ([device.model isEqualToString:@"iPhone"] || [device.model isEqualToString:@"iPhone Simulator"]) {

  if ([[UIScreen mainScreen] bounds].size.height == 480) {
    // Do something with the iPhone
  }
		
  if ([[UIScreen mainScreen] bounds].size.height == 568) {
    // Do something with the iPhone5
  }
}
	
if ([device.model isEqualToString:@"iPad"] || [device.model isEqualToString:@"iPad Simulator"]) {
  // Do something with the iPad
}