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    <p>The answer is unfortunately easy. Subentities across physically different files and/or models is not supported. In the underlying data structure, Core Data will take all sub-entities and flatten them out to a single table. So if you have a Parent, ChildA, ChildB and ChildC each with 4 attributes, then you will end up with a single table with 16 columns.</p> <p>This is why sub-entities are not supported in the manner that you are attempting. Each model is a silo unto itself and can at most have weak references to objects in the other model(s).</p> <h2>Update</h2> <p>It is an issue of "not supported by design" as I explained above. What you are trying to do is not supported because of the way it is persisted in the underlying data structure. Creating sub-entities is not something you should be doing a lot of in the first place because it flattens your data model. </p> <p>Entity inheritance <strong>does not</strong> equal object inheritance. Your objects can inherit in any way, shape or form you want. Entity inheritance should be extremely rare and have a <em>very</em> good reason behind it. </p> <p>Solving parent child relationship issues is one of the few reasons to use entity inheritance. </p> <p>Trying to avoid duplication of columns is <strong>not</strong> a good reason.</p> <p>Since you cannot do parent/child relationships across models (and you do have more than one model even if they are being merged into one <em>instance</em> of the <code>NSManagedObjectModel</code>) it is unlikely to be a reason to do entity inheritance across models that can't be solved via a similar solution.</p>
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    1. POsetIncludesSubentities: in an NSFetchRequest is broken for entities across multiple persistent stores
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    1. USMarcus S. Zarra
    1. USMarcus S. Zarra
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    1. COMaybe this is the right answer, but the terminology here is ambiguous. My app has only one managedObjectModel, but it is created at runtime from multiple xcdatamodels. Why are there all these hooks for reading in multiple models, and saving to multiple persistent stores, if in the interim (in the app) it's broken? This is why I think it's not a "not supported by design" issue but rather a "not supported by ommission/bug" issue. What I'm hoping for is a workaround...
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