How do I animate a view when presenting a UIViewController? - ios

Question

I have a custom alert which is presented as a UIView on a UIViewController. So when I want to present the alert I present the UIViewController which brings up the alert. The problem that I'm having is that I want to do a simple animation on the alert when it's shown. But as it is presented as a UIViewController and not just shown with a UIView overlay, I'm a bit confused as how to accomplish this. Here's the relevant code:
static func standardMessageAlert(title: String, msg: String, action: ((_ text: String?) -> Void)? = nil) -> CustomAlertViewController? {
let alert = CustomAlertViewController.create(title: title, message: msg)
let okAction = CustomAlertAction(title: "OK", type: .normal, handler: action)
alert?.addAction(okAction)
return alert
}
And the code for CustomAlertViewController, which is pretty big, but the create method looks like this:
static func create(title: String?, message: String?, addon: Addon? = nil, alertType: AlertType? = nil) -> CustomAlertViewController? {
let storyboard = UIStoryboard(name: "Overlay", bundle: nil)
guard let viewController = storyboard.instantiateViewController(withIdentifier: "CustomAlertViewController") as? CustomAlertViewController else {
return nil
}
viewController.modalPresentationStyle = .overCurrentContext
viewController.modalTransitionStyle = .crossDissolve
viewController.alertType = alertType
viewController.addon = addon
viewController.alertTitle = title
viewController.alertMessage = message
return viewController
}
...
The alert is presented like this:
func present(animated: Bool, onView: UIViewController? = UIApplication.rootViewController(), completion: (() -> Void)? = nil) {
onView?.present(self, animated: animated, completion: nil)
}
The animation would be something basic like this:
func animateView() {
alertView.alpha = 0
UIView.animate(withDuration: 1, animations: { [weak self] () -> Void in
guard let self = self else { return }
self.alertView.alpha = 1.0
})
}
alertView is the outlet for the alert UIView that is inside the UIViewController. I guess this is what I should animate, but where do I put that code? How do I implement it when the UIViewController is presented? I have also tried using onView.view to animate it. The problem that I see is that if I put the animation code before presenting it's too early, and if it's after presenting then its too late.

Answer 1

If you want to keep this logic then I can suggest you to setup initial view state in viewDidLoad and run animation after viewWillAppear.
But I recommend to use custom transitions