Try setting self.automaticallyAdjustsScrollViewInsets = NO
in your main view controller.
This was introduced in iOS 7
so you might want to wrap that with an iOS version check, if you are supporting iOS 6
and below.
Update
If you are using storyboards, you can do this in the Interface Builder as well as by checking 'Adjust Scroll View Insets'
for your selected controller.
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