IOS 以编程方式创建 UIAlertViewController

IOS create UIAlertViewController programmatically

提问by Lê Khánh Vinh

I'm working on a ViewController with code (no storyboard). I'm trying to add and AlertController

我正在使用代码（没有故事板）处理 ViewController。我正在尝试添加和 AlertController

I have declare propery in .m

我在 .m 中声明了财产

@property (nonatomic, strong) UIAlertController *alertController;

And init in loadviewmethod

并在loadview方法中初始化

//alertviewController
    _alertController = [[UIAlertController alloc]initWithNibName:nil bundle:nil];

And call the alertview in viewDidLoad:

并调用警报视图viewDidLoad：

_alertController = [UIAlertController alertControllerWithTitle:@"Error display content" message:@"Error connecting to server, no local database" preferredStyle:UIAlertControllerStyleAlert];

UIAlertAction *ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
                LandingPageViewController *viewController = [[LandingPageViewController alloc] initWithNibName:nil bundle:nil];
    //            viewController.showNavBarBackButton = YES;
                [[AppDelegate sharedAppDelegate].rootViewController cPushViewController:viewController];
}];
[_alertController addAction:ok];
[self presentViewController:_alertController animated:YES completion:nil];

I dont' know why the alert is not showing up. Some thing wrong with my code. How to set up and call alertViewControllerprogrammatically?

我不知道为什么警报没有出现。我的代码有问题。如何以alertViewController编程方式设置和调用？

回答by ChenSmile

- (void)logoutButtonPressed
{
     UIAlertController * alert = [UIAlertController
                                 alertControllerWithTitle:@"Logout"
                                 message:@"Are You Sure Want to Logout!"
                                 preferredStyle:UIAlertControllerStyleAlert];

    //Add Buttons

    UIAlertAction* yesButton = [UIAlertAction
                                actionWithTitle:@"Yes"
                                style:UIAlertActionStyleDefault
                                handler:^(UIAlertAction * action) {
                                    //Handle your yes please button action here
                                    [self clearAllData];
                                }];

    UIAlertAction* noButton = [UIAlertAction
                               actionWithTitle:@"Cancel"
                               style:UIAlertActionStyleDefault
                               handler:^(UIAlertAction * action) {
                                   //Handle no, thanks button
                               }];

    //Add your buttons to alert controller

    [alert addAction:yesButton];
    [alert addAction:noButton];

    [self presentViewController:alert animated:YES completion:nil];
}

回答by iOS

In Xcode 9.4.1

在 Xcode 9.4.1 中

Create alert function globally and use every where.

全局创建警报功能并在任何地方使用。

//Alert function
- (void) showAlertMsg:(UIViewController *)viewController title:(NSString *)title message:(NSString *)message {

    UIAlertController * alert = [UIAlertController alertControllerWithTitle : title
                                                                    message : message
                                                             preferredStyle : UIAlertControllerStyleAlert];

    UIAlertAction * ok = [UIAlertAction
                          actionWithTitle:@"OK"
                          style:UIAlertActionStyleDefault
                          handler:^(UIAlertAction * action)
                          { }];

    [alert addAction:ok];
    dispatch_async(dispatch_get_main_queue(), ^{
        [viewController presentViewController:alert animated:YES completion:nil];
    });

}

Call like this in your required place.

在您需要的地方这样呼叫。

Import that class and create instance

导入该类并创建实例

//Ex:
GlobalClassViewController *gcvc = [[GlobalClassViewController alloc]init];

//Call alert function with instance
[gcvc showAlertMsg:self title:@"" message:placeholderText];

How would I create a UIAlertView in Swift?

我将如何在 Swift 中创建 UIAlertView？

回答by Ethan Parker

And in Swift >=3:

在 Swift >=3 中：

  let alertController = UIAlertController(title: "Some Error",
                                               message: "Pleas confirm?",
                                               preferredStyle: .alert)

  let defaultAction = UIAlertAction(title: "OK", style: .default, handler: nil)
            alertController.addAction(defaultAction)

  self?.present(alertController, animated: true, completion: nil)

回答by Krunal

Create global Alert controller that is accessible in all view controllers using extension.
Create an extension of UIViewControllerwith your function to display alert with required parameter arguments.

使用扩展创建可在所有视图控制器中访问的全局警报控制器。 使用您的函数
创建扩展UIViewController以显示带有必需参数参数的警报。

extension UIViewController {

      func displayalert(title:String, message:String) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
        alert.addAction((UIAlertAction(title: "OK", style: .default, handler: { (action) -> Void in

            alert.dismiss(animated: true, completion: nil)

        })))

        self.present(alert, animated: true, completion: nil)


      }
}

Now call this function from your view controller:

现在从你的视图控制器调用这个函数：

class TestViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.displayalert(title: <String>, message: <String>)
    }
}