title: Swift cannot assign value of type '()' to type 'String?'
body: <p>I'm learning Swift2/iOS app development. I am confused by an error being thrown by Xcode before compiling. Here is the code throwing the error :</p>
  
  <pre><code>let dotpos = display.text!.rangeOfString(".")
  if dotpos != nil {
      display.text = display.text!.removeRange(dotpos!)
  }
  </code></pre>
  
  <p>The error thrown is (at the line "display.text = display.text!.removeRange(dotpos!)") :</p>
  
  <blockquote>
    <p>Cannot assign value of type '()' to type 'String?'</p>
  </blockquote>
  
  <p>Note : display is a <code>UILabel</code> object.</p>
  
  <p>Could someone point me toward the error I might have done?</p>