popToViewController用法，直接初始化一个VC,而后pop会崩溃。

[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:2] 
animated:YES];
或

for (UIViewController *temp in self.navigationController.viewControllers) {
           if ([temp isKindOfClass:[你要跳转到的Controller class]]) {
              [self.navigationController popToViewController:temp animated:YES];
           }
       }