title: How can I check if a button is pressed during a specific time interval in iOS?
body: <p>I'm creating a game for iOS and need some help.</p>
  <p>Simply put, random letters will be shown in a label(changing at regular interval), and the user must press the button when they recognise a pattern. If they press the button they earn points, and if they miss it, they lose points.</p>
  <p><strong>For example:</strong></p>
  <p>let's say they are looking for a letter repeating over one gap. They see the letters &quot;R K W K&quot;. On the second K they would press the button. I need to be able to check if the button was pressed while that second K was displayed. I have searched here on stack overflow, but I can't really find anything specific to my situation. Thanks in advance for your responses. I'm new here, so I tried to be as specific as possible.</p>