IOS create UIAlertViewController programmatically

Question

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?

Answer 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]; } 

Answer 2

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?