@property(nonatomic, assign) BOOL automaticallyAdjustsScrollViewInsets
YES, which allows the view controller to adjust its scroll view insets in response to the screen areas consumed by the status bar, navigation bar, and toolbar or tab bar. Set to NO if you want to manage scroll view inset adjustments yourself, such as when there is more than one scroll view in the view hierarchy.原文：http://www.cnblogs.com/buakaw/p/5233399.html