title: How to implement the new Core Data model builder 'unique' property in iOS 9.0 Beta
body: <p>In the WWDC15 video session, <a href="https://developer.apple.com/videos/wwdc/2015/?id=220" rel="nofollow noreferrer">'What's New in Core Data'</a> at 10:45 mins (into the presentation) the Apple engineer describes a new feature of the model builder that allows you to specify unique properties. Once you set the those unique properties, Core Data will not create a duplicate object with that property. This is suppose to eliminate the need to check if an identical object before you create a new object.</p>
  
  <p>I have been experimenting with this but have no luck preventing the creation of new objects with identical 'unique' properties (duplicate objects). Other than the 5 minute video explanation, I have not found any other information describing how to use this feature.</p>
  
  <p><img src="https://i.stack.imgur.com/7LoWl.png" alt="enter image description here"></p>
  
  <p>Does anyone have any experience implementing the 'unique' property attribute in the Core Data Model?</p>