How to create uialertcontroller in global swift

swift

Here's what I used, this is the same as @penatheboss answered, just add the ability of adding actions and handlers.

extension UIViewController {
    func popupAlert(title: String?, message: String?, actionTitles:[String?], actions:[((UIAlertAction) -> Void)?]) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        for (index, title) in actionTitles.enumerated() {
            let action = UIAlertAction(title: title, style: .default, handler: actions[index])
            alert.addAction(action)
        }
        self.present(alert, animated: true, completion: nil)
    }
}

Just make sure actionTitles and actions array the same count. Pass nil if you don't need any action handler closure.

self.popupAlert(title: "Title", message: " Oops, xxxx ", actionTitles: ["Option1","Option2","Option3"], actions:[{action1 in

},{action2 in

}, nil])

Objective C:

Add the category for UIViewController

UIViewController+PopAlert.h

#import <UIKit/UIKit.h>

@interface UIViewController (UIViewControllerCategory)
- (void) popAlertWithTitle: (NSString*) title message: (NSString*) message actionTitles:(NSArray *) actionTitles actions:(NSArray*)actions;
@end

UIViewController+PopAlert.m

#import "UIViewController+PopAlert.h"

@implementation UIViewController (UIViewControllerCategory)
- (void) popAlertWithTitle: (NSString*) title message: (NSString*) message actionTitles:(NSArray *) actionTitles actions:(NSArray*)actions {
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];
    [actionTitles enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        UIAlertAction *action = [UIAlertAction actionWithTitle:obj style:UIAlertActionStyleDefault handler:actions[idx]];
        [alert addAction:action];
    }];
    [self presentViewController:alert animated:YES completion:nil];
}
@end

Usage:

#import UIViewController+PopAlert.h

...

[super viewDidDisappear:animated];
    NSArray *actions = @[^(){NSLog(@"I am action1");}, ^(){NSLog(@"I am action2");}];
    [self popAlertWithTitle:@"I am title" message:@"good" actionTitles:@[@"good1", @"good2"] actions:actions];

self.window would mean that there's a window object in this class, and it's not the case.

You would need to use your let window : UIWindow? with window?.presentViewController(alert, animated: true, completion: nil), but this won't help, since this window does not actually represent any existing window, and it's not a view controller anyway.

So I suggest you pass the actual view controller you'll be using to the method:

static func showAlertMessage(vc: UIViewController, titleStr:String, messageStr:String) -> Void {
    let alert = UIAlertController(title: titleStr, message: messageStr, preferredStyle: UIAlertControllerStyle.Alert);
    vc.presentViewController(alert, animated: true, completion: nil)
}

and you call it from a class where a UIViewController object is available.