[iOS] How to change Status Bar Style in iOS 7 / 8

In Info.plist set 'View controller-based status bar appearance' as NO

In AppDelegate add

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
   [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];

}

Reference : 
http://stackoverflow.com/questions/17678881/how-to-change-status-bar-text-color-in-ios-7

[iOS] iOS7 狀態欄無法消失？

//在 root ViewController 中，viewDidload 函式裡增加
if([self respondsToSelector:@selector(setNeedsStatusBarAppearanceUpdate)])
{
    // iOS 7
    [self prefersStatusBarHidden];
    [self performSelector:@selector(setNeedsStatusBarAppearanceUpdate)];
}
else
{
    // iOS 6
    [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationSlide];
}


// 增加此函式
- (BOOL)prefersStatusBarHidden
{
    return YES;
}

如此即可相容 iOS6 & iOS7 的情況。