1. In info.plist set View controller-based status bar appearance to YES
2. In view controllers not contained by UINavigationController implement this method.

In Objective-C:

- (UIStatusBarStyle)preferredStatusBarStyle
{ 
    return UIStatusBarStyleLightContent; 
}

In Swift:

override func preferredStatusBarStyle() -> UIStatusBarStyle {
    return UIStatusBarStyle.LightContent
}