//Calling
[self showMessage:@"There is no internet connection for this device"
withTitle:@"Error"];
//Method
-(void)showMessage:(NSString*)message withTitle:(NSString *)title
{
UIAlertController * alert= [UIAlertController
alertControllerWithTitle:title
message:message
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *okAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action){
//do something when click button
}];
[alert addAction:okAction];
UIViewController *vc = [[[[UIApplication sharedApplication] delegate] window] rootViewController];
[vc presentViewController:alert animated:YES completion:nil];
}
If you want to use this alert in NSObject class you should use like:
-(void)showMessage:(NSString*)message withTitle:(NSString *)title{
dispatch_async(dispatch_get_main_queue(), ^{
UIAlertController *alertController = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];
[alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
}]];
[[[[UIApplication sharedApplication] keyWindow] rootViewController] presentViewController:alertController animated:YES completion:^{
}];
});
}