Present alert controller in main app window? - ios

Question

In my model class i want to show alert when something bad happen (for example, server send an error). However, i dont want to bother with delegate or KVO.
Is there an easy way to show an alert for "main" window, to place a view above others?
Currently i use this code (not work, if placed out of viewController classes):
UIAlertController *vc = [UIAlertController alertControllerWithTitle:#"Произошла ошибка"
message:response
preferredStyle:UIAlertControllerStyleAlert];
[self presentViewController:vc animated:YES completion:^{
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[vc dismissViewControllerAnimated:YES completion:nil];
});
}];
Obviously, classes that don't have a view cant use:
[self presentViewController:vc animated:YES completion:^{

Answer 1

as per solution of #Ashley Mills You can find top view controller with this method
- (UIViewController *)currentTopViewController
{
UIViewController *topVC = [[[[UIApplication sharedApplication] delegate] window] rootViewController];
while (topVC.presentedViewController)
{
topVC = topVC.presentedViewController;
}
if ([topVC isKindOfClass:[UINavigationController class]]) {
return [(UINavigationController *)topVC topViewController];
}
return topVC;
}
show you alert in return object of currentTopViewController method

Answer 2

You need to present the UIAlertController from a UIViewController. If you want the main view controller, you'll need to do this from your application delegate's window's rootViewController.
A nasty way to do this is to refer to UIApplication.sharedApplication().delegate.window.rootViewController
A better way would be to post a notification from your model method and listen for it in the App Delegate
Ideally though you should be looking at passing back an error from your model method to the calling view controller.
Or perhaps you could pass in your current view controller as a parameter to the model method