Show alert when screenshot is taken and require text input

Question

Wanted to see if there was a way to display an alert view after screenshot is taken, and then require text input that matches a specific string. If the user doesn't input the right text, then the alert view doesn't dismiss and the user is prompted to retry. If the user inputs the correct text, the alert view is dismissed.

Answer 1

You could use this

let requireTextInput = "require text input"
// add observer for screen shot    
NotificationCenter.default.addObserver(forName: NSNotification.Name.UIApplicationUserDidTakeScreenshot, object: nil, queue: OperationQueue.main, using:
        { notification in

            var inputTextField = UITextField()

            let textPrompt = UIAlertController(title: nil, message: "require text input", preferredStyle: .alert)

            textPrompt.addAction(UIAlertAction(title: "Cancel", style: .default, handler: nil))

            textPrompt.addAction(UIAlertAction(title: "OK", style: .default, handler: {
                (action) -> Void in
            // if the input match the required text

                let str = inputTextField.text
                if str == requireTextInput {
                    print("right")
                } else {
                    print("wrong")
                }

            }))

            textPrompt.addTextField(configurationHandler: {(textField: UITextField!) in
                textField.placeholder = "place Holder"
                inputTextField = textField

            })

            self.present(textPrompt, animated: true, completion: nil)

    })