edgesForExtendedLayout not working

I have been reading a lot about iOS7 UI transition.

I am not able to get what these three properties automaticallyAdjustsScrollViewInsets, extendedLayoutIncludesOpaqueBars, edgesForExtendedLayout??

For example I am trying to make my view controllers start below the status bar but I am not able to achieve it.

You can see in image aboutus button and search button ... view doesn't start properly . it start from top status bar.

Actually in ios 6 it start from below the status bar.

i have create a ui progrmatically (I am not using storyboard ).

I have google and got following solution but it wont work I have write following code in my Homeviewcontroller

if([self respondsToSelector:@selector(edgesForExtendedLayout)]){ self.edgesForExtendedLayout =UIRectEdgeNone;}

My rootviewcontroller is tab bar i also tried this but did'nt get success

if([self respondsToSelector:@selector(edgesForExtendedLayout)]){ self.tabBarController.edgesForExtendedLayout =UIRectEdgeNone;}

please advise me i dont know what am i doing wrong?Thanks in advance