Core Data will attempt to migrate from whatever version the user currently has on their device directly to version 3 of your app/model, e.g., from version 1 to 3, or from version 2 to 3.
Along these lines, here’s a good guide to follow when you need to make changes to your managed object model, to help ensure a smooth migration process (you’ll be going through these steps shortly): Imagine how complex this could get once you’ve released a dozen or more versions!
The class extension should now look like this: Control-drag from the empty UIText View (below the “What” UILabel) to the extension in Detail View Controller.m in the right editor, right below the where Text Field property declaration you just made and release.
In the pop-up that appears, enter what Text View for Name and click Connect.
Control-drag from the empty UIText Field (to the right of the “Where” UILabel) to the extension in Detail View Controller.m in the right editor, right below the when Label property declaration you just made and release.