title: Objective C - How to concatenate an entire array of strings?
body: <p>I am an Objective C newbie. I want to write a method that takes in an array of strings and returns a concatenated string, with a comma (,) in between each string. 
  So if an array is {a b c d}, I want to return a,b,c,d.</p>
  
  <p>What is the easiest way to do that?</p>