29.pop到指定Controller的三个方法

返回根页面vc用 ：

[self.navigationController popToRootViewController］

返回指定的某个vc用下面（通过index定位） 

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

或（通过class定位）

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