Swift 4中带有返回布尔值的UIAlertView共享类

func showAlertWithConfirmation(completion: @escaping (Bool) -> Void) {
    let alertController = UIAlertController(title: "Confirmation", message: "Are you sure?", preferredStyle: .alert)
    
    let confirmAction = UIAlertAction(title: "Yes", style: .default) { (_) in
        completion(true)
    }
    alertController.addAction(confirmAction)
    
    let cancelAction = UIAlertAction(title: "No", style: .cancel) { (_) in
        completion(false)
    }
    alertController.addAction(cancelAction)
    
    // 在适当的地方显示弹窗
    // present(alertController, animated: true, completion: nil)
}