title: Crash set variable extension Swift
body: <p>I got a crash when i try to set a variable inside a extension:</p>
  
  <pre><code>extension String {
   var index: Int {
      get {
          return self.index
      }
      set {
          self.index = newValue
      }
   }
  }
  
  var o: String = "tre"
  
  
  o.index = 87 // crash here
  println(o.index) // Even here
  </code></pre>
  
  <p>i tried everything, without any success.
  Thanks in advance for your help.</p>