好用的A->B->C 之后 C->A

NSInteger num = self.navigationController.viewControllers.count;

if (num > 3) {

UIViewController *popVC =    self.navigationController.viewControllers[num - 3];

[self.navigationController popToViewController:popVC animated:YES];

}

以下是文章链接 

http://www.jianshu.com/p/c4d1eb226eaf