Storing images in Core Data or as file?

Question

I have set of data which contains images also. I want to cache this data. Should i store them on file system or on core data and why?

Answer 1

You might want to read this from the Core Data Programming Guide on how to deal with binary large objects (BLOBs). There are rules of thumb for what size binary data should and should not be stored within the actual Core Data store.

You might also look at Core Data iPad/iPhone BLOBS vs File system for 20k PDFs

If you do place binary data within Core Data store, you would do well to have a "Data" entity that holds the actual data and to have your "Image" entity separate. Create a relationship between the two entities, so that "Data" need only be loaded when actually needed. The "Image" entity can hold the meta-data such as title, data type, etc.

Answer 2

With regards to where to store the user data/files (I found "application support" to be a decent location given that i was wary of the user moving, deleting or altering the file in some way that would result in the image not being able to be recovered and used later by my application)

Take minecraft as an example: eg. "~/Library/Application Support/minecraft/saves/"

I would agree with the previous comments and store paths to the images in core data but otherwise store the images themselves as png files in their own folder outside of core data.

Answer 3

There are two main options:

1. Store the file on disk, and then store the path to the image in core data
2. Store the binary data of the image in core data

I personally prefer the 1st option, since it allows me to choose when I want to load the actual image in memory. It also means that I don't have to remember what format the raw data is in; I can just use the path to alloc/init a new UIImage object.