title: What is the method signature when it uses an external param name in Swift
body: <p>I'm using an NSTimer object in my Swift code, which requires a method signature to be passed to its 'selector' parameter in order to recurrently perform said method. When the method  signature does not have an external parameter name i.e.</p>
  
  <pre><code>func timerMethod(internal: String) { ... }
  </code></pre>
  
  <p>I can pass the timer object this signature as so:</p>
  
  <pre><code>var timer = NSTimer.scheduledTimerWithTimeInterval(1.0,
          target: self,
          selector: Selector("timerMethod:"),
          userInfo: userInfo,
          repeats: true)
  </code></pre>
  
  <p>However, if I give the method a signature with an external parameter name, such as:</p>
  
  <pre><code>func timerMethod(external internal: String) { ... }
  </code></pre>
  
  <p>I can't figure out how to call the method. I attempted to log it using:</p>
  
  <pre><code>println("\(__FUNCTION__)")
  </code></pre>
  
  <p>Which logs the following: </p>
  
  <pre><code>timerMethod(external:)
  </code></pre>
  
  <p>But whenever I try this or any of the following, I receive 'unrecognized selector' exceptions:</p>
  
  <pre><code>timerMethod:
  timerMethod:external
  timerMethod:external:
  timerMethod:(external)
  timerMethod:(external:)
  timerMethod(external):
  </code></pre>
  
  <p>Stumped for now. Anybody running into something similar?</p>