IOS create UIAlertViewController programmatically

问题

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

I have declare propery in .m

@property (nonatomic, strong) UIAlertController *alertController;

And init in loadview method

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

And call the alertview in 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 alertViewController programmatically?

回答1:

- (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2:

And in Swift >=3:

  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3:

In Xcode 9.4.1

Create alert function globally and use every where.

//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.

Import that class and create instance

//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?

回答4:

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

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:

class TestViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

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

来源：https://stackoverflow.com/questions/38702269/ios-create-uialertviewcontroller-programmatically

标签

ios

objective-c

uialertview