Storyboardで3.5inchディスプレイに手っ取り早く対応する。 ref: http://qiita.com/g-1/items/074aa4a3f0f886e271ec

AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  //3.5inchと4inchを読み分けする
  CGRect rect = [UIScreen mainScreen].bounds;
  if (rect.size.height == 480) {
    UIStoryboard* storyboard = [UIStoryboard storyboardWithName:@"3_5_inch" bundle:nil];
    UIViewController* rootViewController = [storyboard instantiateInitialViewController];

    self.window.rootViewController = rootViewController;
  }

  return YES;
}