how to use UIAlertController - ios

Question

I am trying to use this code in a Pacman game I got from some website but had to change UIAlertView to UIAlertController except the following code has two errors that I don't know how to fix (I am really new to programming and feel like this is a really newbie question - sorry!!)
The first error is in line 4: No known class method for selector alertControllerWithTitle
A second error is in the last line: no visible interface declares the selector show
- (void)collisionWithExit: (UIAlertController *)alert {
if (CGRectIntersectsRect(self.pacman.frame, self.exit.frame)) {
[self.motionManager stopAccelerometerUpdates];
UIAlertController *alert = [UIAlertController alertControllerWithTitle:#"Congratulations"
message:#"You've won the game!"
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil
preferredStyle:UIAlertControllerStyleAlert];
[alert show];
}
}

Answer 1

Please check the following code:
UIAlertController* alert = [UIAlertController alertControllerWithTitle:#"My Alert"
message:#"This is an alert."
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:#"OK" style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {}];
[alert addAction:defaultAction];
[self presentViewController:alert animated:YES completion:nil];

Answer 2

Check below this code.
for Objective-C:
UIAlertController *alert = [UIAlertController alertControllerWithTitle:#"Alert" message:#"Message" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *ok = [UIAlertAction actionWithTitle:#"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
//button click event
}];
UIAlertAction *cancel = [UIAlertAction actionWithTitle:#"Cancel" style:UIAlertActionStyleCancel handler:nil];
[alert addAction:cancel];
[alert addAction:ok];
[self presentViewController:alert animated:YES completion:nil];
for Swift 4.x:
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { action in
switch action.style {
case .default:
print("default")
case .cancel:
print("cancel")
case .destructive:
print("destructive")
}
}))
self.present(alert, animated: true, completion: nil)

Answer 3

Swift 5: Simple Extension
extension UIViewController {
func presentAlert(withTitle title: String, message : String, actions : [String: UIAlertAction.Style], completionHandler: ((UIAlertAction) -> ())? = nil) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
for action in actions {
let action = UIAlertAction(title: action.key, style: action.value) { action in
if completionHandler != nil {
completionHandler!(action)
}
}
alertController.addAction(action)
}
self.present(alertController, animated: true, completion: nil)
}
}
Usage:
self.presentAlert(withTitle: "Network Error", message: "Please check your internet connection", actions: [
"Retry" : .default, "Cancel": .destructive] , completionHandler: {(action) in
if action.title == "Retry" {
print("tapped on Retry")
}else if action.title == "Cancel" {
print("tapped on Cancel")
}
})
OR
self.presentAlert(withTitle: "Mail services are not available", message: "Please Configure Mail On This Device", actions: ["OK" : .default] , completionHandler: nil)