几秒后如何关闭 UIAlertController？

Question

我需要展示一个没有提交按钮的框，但是让它在3秒后消失。是否可以添加任何超时？

  UIAlertController * alert=   [UIAlertController
                                alertControllerWithTitle:@"Please wait, checking your PAID INVOICE, to allow the service."
                                message:"...waiting..."
                                preferredStyle:UIAlertControllerStyleAlert];

  [self.window.rootViewController presentViewController:alert animated:YES 
  completion:nil];   

- user285594

Answer 1

下面的代码可能会起到作用：

UIAlertController *alert=   [UIAlertController
                                alertControllerWithTitle:@"Please wait, checking your PAID INVOICE, to allow the service."
                                message:"...waiting..."
                                preferredStyle:UIAlertControllerStyleAlert];

[self.window.rootViewController presentViewController:alert animated:YES 
  completion:nil]; 


dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

        [alert dismissViewControllerAnimated:YES completion:^{

            //Dismissed
        }];

});

- Ronak Chaniyara

---

这会导致重复的代码，如果需要多次使用该函数。 - CZ54

不错的想法，但是你应该将调度/解散代码添加到 presentViewController 的 completion: 块中。 - Ashley Mills

Answer 2

继@RonakChaniyara的回答之后，这个添加了一个测试，以确保警告仍然会显示（例如，如果警告有一个用于解除的按钮）。

[presentViewController:alert animated:YES completion: {

    // Dispatch 3 seconds after alert presented
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

        // Check that alert is still presented
        if self.presentedViewController == alert {
            // Dismiss if it is
            [self.dismissViewControllerAnimated:YES completion:^{    
                //Dismissed
            }];    
        }
    });
}]; 

在Swift中...

let alert = UIAlertController(title: "Please Wait", message: "…waiting…", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .cancel, handler: nil))

present(alert, animated: true) {
    DispatchQueue.main.asyncAfter(deadline: .now() + 3) { [weak self] in
        guard self?.presentedViewController == alert else { return }

        self?.dismiss(animated: true, completion: nil)
    }
}

- Ashley Mills

Answer 3

您可以尝试以下方法：

您可以像这样尝试：

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)),     dispatch_get_main_queue(), ^{
    [alert dismissViewControllerAnimated:YES completion:nil];
});

- Andney

---

这会导致重复的代码，如果需要多次使用该函数。 - CZ54

Answer 4

在你的alertController中添加performSelector，并将UIAlertController对象创建为全局对象。

 [self performSelector:@selector(hideAlertView) withObject:nil afterDelay:3.0];

-(void)hideAlertView{
 [alert dismissViewControllerAnimated:YES completion:nil];  // or use [self dismissViewControllerAnimated:alert completion:nil];
}

- Anbu.Karthik

Answer 5

您可以使用此代码来关闭您的UIAlertController。 您需要全局声明UIAlertController。

[self performSelector:@selector(removeAlert) withObject:nil afterDelay:3];

您的选择器方法

-(void)removeAlert{
    [self dismissViewControllerAnimated:alert completion:nil];
}

- Sunny

Answer 6

你也可以尝试这个： 对于Objective-C

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"message" preferredStyle:UIAlertControllerStyleAlert];
    [self presentViewController:alertController animated:YES completion:^{
        [self performSelector:@selector(dismissAlertController:) withObject:alertController afterDelay:3.0];
    }];

    - (void)dismissAlertController:(UIAlertController *)alertController {
        [alertController dismissViewControllerAnimated:YES completion:nil];
    }

对于Swift 3

    let alertController = UIAlertController(title: "Title", message: "message", preferredStyle: .alert)
    present(alertController, animated: true) { 
        self.perform(#selector(ViewController.dismissAlertController(alertController:)), with: alertController, afterDelay: 3.0)
    }

    internal func dismissAlertController(alertController: UIAlertController) {
        alertController.dismiss(animated: true, completion: nil)
    }

- abdullahselek

Answer 7

最好的方法是将UIAlertController子类化为您自己的类，并在viewDidAppear中添加一个NSTimer以自动解除。不要忘记在viewDidDisappear方法中使计时器无效并释放它。

- CZ54

---

糟糕的想法...你过于复杂化了事情！ - Ashley Mills

为什么这样说？子类化过于复杂？重用代码也是如此吗？还有可测试性？ - CZ54

很好的回答，但是提供一段代码示例会更好。 - arao6