title: in-app purchase in Swift with a single product
body: <p>Is there a simple way to implement a in-app purchase in swift for a single product?</p>
  
  <p>I want a button that triggers the in-app purchase like a [ad-removal] or [unlock-premium-content]</p>
  
  <p>I can't understand the full logic of it.</p>
  
  <p>I'm trying to follow and translate this tutorial from [Techotopia] <a href="http://www.techotopia.com/index.php/An_iOS_7_In-App_Purchase_Tutorial">http://www.techotopia.com/index.php/An_iOS_7_In-App_Purchase_Tutorial</a></p>
  
  <p>But It's my first time with the StoreKit Framework, and also with Swift.</p>
  
  <p>I just want to know the logic of the in-app purchase transaction with the Swift StoreKit Framework.</p>
  
  <p>Thanks!</p>