which is the best way to check the validity of the subscription in a UIViewController class and to perform an action if the subscription is valid.
`class LoadScreenViewController: UIViewController {
static let sharedInstance = LoadScreenViewController()
//ActivityIndicator Declarieren
var activityIndicator:UIActivityIndicatorView = UIActivityIndicatorView()
override func viewDidLoad() {
super.viewDidLoad()
// from here check the subscription (InAppPurchase.swift) and do an actionon
//ActivityIndicator Implementieren um das Ladesymbol anzuzeigen
activityIndicator.center = self.view.center
activityIndicator.hidesWhenStopped = true
activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.white
view.addSubview(activityIndicator)
activityIndicator.startAnimating()
DispatchQueue.main.asyncAfter(deadline: .now() + 12.0) { // Change `2.0` to the desired number of seconds.
self.activityIndicator.stopAnimating()
self.selectSubscription // select a subscriptionon
}
}`