safety1.swift

struct UserConfirmationRequired {
    
    private let performDestructiveAction: () -> ()
    
    init(destructiveAction: @escaping () -> ()) {
        self.performDestructiveAction = destructiveAction
    }
    
    func performWithUserConfirmation(alertTitle: String,
                                     alertMessage: String,
                                     alertDestructiveActionTitle: String,
                                     completion: @escaping (Bool) -> ()) {
        
        // retrieving view controller to show alert from
        guard let window = UIApplication.shared.delegate?.window else {
            print("No window")
            completion(false)
            return
        }
        guard let viewController = window?.rootViewController else {
            print("No view controller")
            completion(false)
            return
        }
        
        // creating and showing an alert
        let alert = UIAlertController(title: alertTitle,
                                      message: alertMessage,
                                      preferredStyle: .actionSheet)
        let cancel = UIAlertAction(title: "Cancel",
                                   style: .cancel,
                                   handler: { _ in completion(false) })
        let destructive = UIAlertAction(title: alertDestructiveActionTitle,
                                        style: .destructive,
                                        handler: { _ in
                                            self.performDestructiveAction()
                                            completion(true)
        })
        alert.addAction(cancel)
        alert.addAction(destructive)
        viewController.present(alert, animated: true)
    }
    
}