title: Assign action to UITextField and update UILabel
body: <p>I am currently using Swift 4 and struggling with a problem which probably is quite simple but I can't find a simple solution to it. I'm gonna try to explain it as thorough as I can.</p>
  
  <p>By using a text field I want to assign an action to the <strong>Send</strong> button on the virtual keyboard to submit the input text and then I want to clear the text field. After the text have been submitted I want to check if the submitted text is equal to a specified String (for example "hello, playground"). If the submitted text is equal to "hello, playground" and thereby correct, I want to update a label to tell the user "Correct"</p>
  
  <p>So the process looks like this:</p>
  
  <p>Text field -> Input text -> Submit text using virtual <strong>Send</strong> button -> Clear text field -> Check if submitted text = specified String -> If yes, update label to "Correct" -> If no, do nothing -> repeat until correct.</p>
  
  <p>I hope it is understandable and thanks in advance.</p>