当使用autolayout 来布置scrollview，转屏时如果使用
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration就能解决这个问题了
ios scrollview autolayout rotation错误
原文：http://blog.csdn.net/dauihiy/article/details/45667299