ios - 在 iOS 中按下返回按钮时如何创建确认弹出窗口？

Question

我想在有人按下我的 iOS 应用程序的“后退”按钮时添加一个弹出窗口，询问用户是否真的想回来。然后，根据用户的响应，我想撤消操作或继续。我试图在我的 View 的 viewWillDisappear 函数中添加代码，然后编写适当的委托(delegate)但它不起作用，因为它总是更改 View 然后显示弹出窗口。我的代码是:

    -(void) viewWillDisappear:(BOOL)animated {
       _animated = animated;
       if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) {
           UIAlertView *alert_undo = [[UIAlertView alloc] initWithTitle:@"UIAlertView"
                                                                message:@"You could be    loosing information with this action. Do you want to proceed?"
                                                               delegate:self
                                                      cancelButtonTitle:@"Go back"
                                                      otherButtonTitles:@"Yes", nil];
           [alert_undo show];
       }
       else [super viewWillDisappear:animated];
   }

委托(delegate)实现是:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    NSString *title = [alertView buttonTitleAtIndex:buttonIndex];
    if([title isEqualToString:@"Yes"])
    {
        [super viewWillDisappear:_animated];
    }
}

这根本不起作用。现在有没有人有更好的方法来做到这一点或者可能有什么问题？

非常感谢，

Answer 1

一次-viewWillDisappear:被称为，没有停止你的 viewController免于消失。

理想情况下，您应该覆盖 navigationBar的后退按钮并在其方法中显示警报(其余部分几乎相同)

- (void)viewDidLoad
{
    //...
    UIBarButtonItem *bbtnBack = [[UIBarButtonItem alloc] initWithTitle:@"Back"
                                                                 style:UIBarButtonItemStyleBordered
                                                                target:self
                                                                action:@selector(goBack:)];

    [self.navigationItem setBackBarButtonItem: bbtnBack];
}

- (void)goBack:(UIBarButtonItem *)sender
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert"
                                                    message:@"...Do you want to proceed?"
                                                   delegate:self
                                          cancelButtonTitle:@"No"
                                          otherButtonTitles:@"Yes", nil];
    [alert show];
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    switch(buttonIndex) {
        case 0: //"No" pressed
            //do something?
            break;
        case 1: //"Yes" pressed
            //here you pop the viewController
            [self.navigationController popViewControllerAnimated:YES];
            break;
    }
}

注意:不要忘记声明 <UIAlertViewDelegate> 在这个 viewController 的 .h 文件中