title: "Ambiguous reference to member map" from concrete type
body: <p>Here is my code. It uses <code>CBUUID</code> which is from Core Bluetooth. Let's just assume the cast of <code>v</code> is valid.</p>
  
  <pre><code>import UIKit
  import CoreBluetooth
  
  func convert(v: AnyObject) -&gt; [String: String] {
      return (v as! [CBUUID: NSData]).map { (uuid, data) in
          (uuid.UUIDString, NSString(data: data, encoding: NSUTF8StringEncoding) ?? "") 
      }
  }
  </code></pre>
  
  <p>The idea is to get the string representation of the dictionary by calling <code>CBUUID.UUIDString</code> for <code>CBUUID</code> and by calling the appropriate <code>NSString</code> constructor for <code>NSData</code>.</p>
  
  <p>I've cast the dictionary to a specific type. Why do I get <strong>"ambiguous reference to member 'map'"</strong> here?</p>