pop到指定Controller的三個方法

返回根頁面vc用 ：

[self.navigationController popToRootViewController］

返回指定的某個vc用下面（通過index定位） 

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

或（通過class定位）

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