title: UITableViewCell styling resetting when scrolled off and back onto view
body: <p>I currently have a TableView in my project, which is set up to turn a cell green when it is pressed, and back to clear if it is pressed a second time. However, if I scroll down to the bottom of the table view, and scroll back up, all my cells have been reset to their default clear colour.</p>
  
  <p>I'm not sure how to go about fixing this issue, as anything I can find referring to it is in Objective-C rather than Swift. Any help and advice as to how to go about this would be great, thanks.</p>