Transient property KVO on private queue context save
Transient property KVO on private queue context save
- Subject: Transient property KVO on private queue context save
- From: Rick Mann <email@hidden>
- Date: Thu, 27 Jun 2013 15:03:03 -0700
I have an Entity with a transient UIImage* property "image." The getter and setter manage an iVar and read and write the image data to disk as a PNG file.
So, I create an Entity in my main MOC, observe the image property on it, then hand it to a child MOC to do some processing. The child fetches a new Entity based on its NSManagedObjectID, and goes to work. When it is done generating the image, it assigns it to the image property, then saves the MOC.
My code is observing the main instance's image property, but this doesn't fire on save. Other, persisted properties do fire.
I presume that if I were to back the image property with a persisted property and store the image data in Core Data, I could get it to fire, perhaps using +keyPathsForValuesAffectingImage. But I wanted to write the image data separately (not too worried about bloating Core Data, but I do like being able to inspect the image file during debugging).
Is this usage not possible (without some additional property to trigger on that is persisted, like lastModified date or something)?
I do have the image property listed in the Model as an undefined transient property.
--
Rick
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