Question

我希望有人可以帮我解决这个问题......我是初学者Xcode / Objective-C程序员。我正在开发一个上学期延续的应用程序。

1：所以我创建了一个按钮，我需要它来执行这个自定义功能：

- (void)cancelTapped {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Notification" message:@"Do you want to delete everything and go back to product selection?" delegate:self cancelButtonTitle:@"No" otherButtonTitles:@"Yes"];
    [alert setTag:1];
    [alert show];
}

我如何/在何处放置此功能？它是在按钮属性中吗？或者我会在自定义类/控制器中编写它并将其链接到它？

2：如何让它听取警报返回： - alertView:didDismissWithButtonIndex:

3：从那里，我如何编写逻辑来隐藏页面并弹出视图？

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {
    if (alertView.tag == 1 && buttonIndex == 1) {
        // Delete data and return to lobby
        [self.navigationController popViewControllerAnimated:YES];
    }
}

Answer 1

您需要一个自定义的UIViewController来容纳按钮和警报视图交互的逻辑。我假设你知道怎么做。

完成后，假设您在视图控制器中有对按钮属性的引用，您可以以编程方式将目标添加到按钮并将选择器cancelTapped作为参数传递：

[myButton addTarget:self action:@selector(cancelTapped) forControlEvents:UIControlEventTouchUpInside];

或者，您可以控制 - 从Storyboard中的按钮拖动到自定义UIViewController的头文件，并定义IBAction。这将在您的实现中创建一个空的cancelTapped方法，然后您可以在其中添加逻辑。

至于收听UIAlertView消息，你需要通过传递＆＃34; self＆＃34;来使你的自定义UIViewController成为UIAlertView的委托。作为以下声明中的代表：

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Notification" message:@"My Message" delegate:self cancelButtonTitle:@"No" otherButtonTitles:@"Yes"];

您的CustomViewController也应该声明为UIAlertViewDelegate。

<强> CustomViewController.h

@interface CustomViewController : UIViewController<UIAlertViewDelegate>
@end

希望这有帮助！

Answer 2

使用VIewWillDisappear方法导航到NavigationItem的detect the press of The back button：

-(void) viewWillDisappear:(BOOL)animated {
    if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) {
       // Navigation button was pressed. Do some stuff 
      [self cancelTapped];

    }
    [super viewWillDisappear:animated];
}
- (void)cancelTapped {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Notification" message:@"Do you want to delete everything and go back to product selection?" delegate:self cancelButtonTitle:@"No" otherButtonTitles:@"Yes"];
    [alert setTag:1];
    [alert show];
}

更多信息＆amp;＆amp;还有Custom UIBArButtonItem Check Here

如何让UIBarButton执行自定义函数？

2 个答案: