Objective-C / Cocoa: Uploading Images, Working Memory, And Storage.

Question

Hello. I'm in the process of porting an application originally in java to cocoa, but I'm rewriting it to make it much better, since I prefer cocoa a lot anyway.

One of the problems I had in the application, was that when you uploaded images to it, I had the images created, (as say an NSImage object) and then I just had them sitting in memory, the more I uploaded the more memory they took up, and I ended up running out of memory.

My question is this: if I am going to have users upload images to this application in cocoa, how should I go about storing them? I don't just want to copy the file paths, because I want what is saved to contain the images, etc. Is there any way to upload an image and copy it into a different place only for my application? Then load that image with the new path name as needed?

Only I would like it all to be consolidated. I'm going to implement saving by archiving one "master" object into an NSData*- so I'd like the images to be saved with that.

Is there a temporary location maybe where I could write the images to disk for my application, and then when I saved, they would all be archived into a single file? Also, how do I do this? Thanks.

Answer 1

If you only want to store the images temporarily, you can store the images in the temporary folder that you get by calling NSTemporaryDirectory(). You would then be able to load the images only when you need to display them.

If you want to save the images with your document then you should investigate using a package format for your document, so that the document is actually a folder containing your images and your archived data file. You can create a file wrapper containing all the files for your document bundle using the various methods of NSFileWrapper and then you would implement the -fileWrapperOfType:error: method of NSDocument in order to handle saving.

This would allow you to store the images unaltered and then lazily load them from the document bundle when required.