title: In Swift, how to insert formatted Int value into String?
body: <p>This seems like a super basic question, but I just can't seem to find the answer anywhere :-(  I am able to do this in Objective C, but I am getting stuck in Swift.</p>
  
  <p>What I need to do:</p>
  
  <ol>
  <li>Take an Integer value</li>
  <li>Format it into a localized string</li>
  <li>Inject the value into another string using the <code>stringWithFormat</code> equivalent method (since the other string is localized as well, which is not shown in simplified examples below)</li>
  </ol>
  
  <p>How it's easily done in <strong>Objective C</strong> -- this works:</p>
  
  <pre><code>    // points is of type NSNumber *
  
      NSNumberFormatter *formatter = [NSNumberFormatter new];
      formatter.locale             = [NSLocale currentLocale];
      formatter.numberStyle        = NSNumberFormatterDecimalStyle;
  
      NSString *ptsString = [formatter stringFromNumber:points];
      NSString *message   = [NSString stringWithFormat:@"You've earned %@ points", ptsString];
  </code></pre>
  
  <p>My best attempt at doing this in <strong>Swift</strong> -- compiler error on last line:</p>
  
  <pre><code>    // points is of type Int
  
      let formatter         = NSNumberFormatter()
      formatter.locale      = NSLocale.currentLocale()
      formatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
  
      let ptsString = formatter.stringFromNumber(points)!
      let message   = String(format: "You've earned %@ points", arguments: ptsString)
  </code></pre>
  
  <p>I'm getting the following error in Xcode on that last line:</p>
  
  <pre><code>"Cannot convert value of type 'String' to expected argument type '[CVarArgType]'"
  </code></pre>
  
  <p><em>(In my actual code, the message into which I want to insert the points value is itself localized as well, but I have simplified this example, as I'm getting the exact same error in both cases.)</em></p>
  
  <p>What am I missing here..?</p>
  
  <p>Thanks so much for any help,</p>
  
  <p>Erik</p>