在父视图上加上如下代码：
self.navigationItem.hidesBackButton = YES;
self.navigationController.interactivePopGestureRecognizer.delegate = self;
self.navigationController.interactivePopGestureRecognizer.enabled = YES;
注：backButton 实际上是在父视图上的
原文地址：http://blog.csdn.net/u011344883/article/details/41909235
