title: CoreData: Dealing with polymorphic associations?
body: <p>I'm not sure if I'm using the correct term here, but let's say I have four entities in my model: <code>Person</code>, <code>Place</code>, <code>Tag</code>, and <code>Photo</code>. Any of the other three entities can have a <code>Photo</code> related to it. Sometimes a <code>Person</code> will have taken the photo and will attach it to a <code>Tag</code>, or a <code>Place</code>, or even another <code>Person</code>. What is the best way to approach polymorphic associations in CoreData?</p>