title: Can't call function with Swift Closure as argument
body: <p>I've written a function to make a web service call, get some JSON, form an array with the data, and return it in a closure on completion. I'm new with this syntax, but the compiler says it's right so I'm assuming it is.</p>
  
  <pre><code>class APIHelper: NSObject {
  
      func getArticles(completion: (result: NSArray, error: NSError)-&gt;()) {
  
      }
  }
  </code></pre>
  
  <p>My problem is, I can't figure out how to call this method. When I try to, the autocomplete doesn't show my completion closure. Instead it acts like I'm supposed to pass that method an instance of the class it's declared in (APIHelper).</p>
  
  <pre><code>//View Controller
  override func viewDidLoad() {
      super.viewDidLoad()
  
      APIHelper.getArticles( { (result: Array!, error: NSError!) -&gt; Void in
  
      })  //COMPILER ERROR: '(NSArray!, NSError!) -&gt; Void' is not convertible to 'APIHelper'
  }
  </code></pre>
  
  <p>Has anyone else gotten this error before? If so, how can I call this method and implement the closure?</p>