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Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)
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Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)


  • Subject: Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)
  • From: mmalcolm crawford <email@hidden>
  • Date: Fri, 29 Apr 2005 16:25:13 -0700


On Apr 29, 2005, at 2:32 PM, Scott Ellsworth wrote:

Faulting only applies to relationships (so in your example comments will be loaded along with the other attributes on fetch), and is only really relevant if you use a SQLite store since it can fetch data on an as-needed basis. The other stores -- XML and binary -- both load the whole persistent store into memory when they're accessed.

What about fetched properties? The docs imply a lazy fetch, but I have not had a chance to test.


Fetched properties are fetched lazily, then cached. If you want to update the cache, then (as with other updates) you refault the object.

On the other hand, I am not sure I grok when I would use a fetched property, as opposed to a stored fetch request. Is there an implicit "must be in a relatioship with the entity that the fetched property is a part of" condition on a fetched property, or some such?

Think of how you might represent a smart playlists in iTunes. You could use a fetch request in place of a fetched property, but this requires a different (and "explicit") code structure -- that is, you'll have to retrieve the fetch request from the model then execute it. The fetched property specifies a relationship (albeit a weak one). It's more natural to ask a (smart) Playlist for its Tracks than to create and execute a fetch request for Track to match a predicate. Moreover, you then have to maintain the set of results yourself rather than it being associated with a particular Playlist...

mmalc

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  • Follow-Ups:
    • Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)
      • From: Scott Ellsworth <email@hidden>
References: 
 >Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: Marc Blatt <email@hidden>)
 >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: mmalcolm crawford <email@hidden>)
 >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: Jim Correia <email@hidden>)
 >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: mmalcolm crawford <email@hidden>)
 >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: Scott Ellsworth <email@hidden>)

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