One of the tenets of iOS 7’s new UI is full screen content. To make full use of the screen, the OS now expects your app will extend underneath the Status Bar at the top of the screen. Apple has created a new set of API’s to allow your apps to take advantage of this new feature.
First, gone are the old UIStatusBarStyleBlackOpaque and UIStatusBarStyleBlackTranslucent. These have been deprecated in favor of UIStatusBarStyleDefault and UIStatusBarStyleLightContent. If you have light background colors behind the Status Bar, use UIStatusBarStyleDefault and the system will use a black color for the time, carrier, and other elements in the Status Bar.