title: What do the different symbols in the API section of the XCode Documentation mean?
body: <p>Looking at the API section on the left side of the XCode Documentation, I've always wondered what the symbols mean?</p>
  
  <p>For instance, there's a "K" in a green square, a "T" in an orange square, an "M" in a blue square, etc.</p>
  
  <p>Is there a key for these?</p>
  
  <p>Thanks!</p>
  
  <p>Rashiki</p>