iOS - Caching and loading images asynchronously

Question

I want an image loading and caching library for iOS that

• loads images asynchronously,
• caches images, with a configurable cache size and LRU behaviour,
• checks to see if images have been updated, using HTTP HEAD,
• doesn't cache anything in the event of an error code or an invalid image.

I've looked at HJCache , but it only satisfies the first two of these criteria. Is there something better?

Answer 1

I know that this thread has been answered, but I have tried a library that has worked great. I was using ASIHttpRequest before and the difference is big.

https://github.com/rs/SDWebImage

Also, if someone needs to Resize or Crop the remote images, and have the same features that SDWebImage provide, I have integrated SDWebImage library with UIImage+Resize library (by Trevor Harmon), and created an example project. I modified the code of SDWebImage to deal with transformations (crop, resize).

The project is public on https://github.com/toptierlabs/ImageCacheResize . Feel free to use it!

Answer 2

EDIT : ASI has been deprecated now but @Tony's answer has a link to a library that seems to do most of this (disclaimer - I've not yet tried it and am going by @Tony's recommendation!)

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ASIHTTPRequest does all of that :)

All you would have to do is add something like to the success callback

UIImage *image = [UIImage imageWithData:[request responseData]];

// If the image is nil ASIHTTPRequest will let you remove the data from the cache
// but I can't remember off the top of my head how. Checkout the docs!

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EDIT

And when you've finished it, you could always pop it onto github for the rest of us . . .

Answer 3

I had a look recently for the sort of thing you describe -- either a general data cache, or an image centric one -- and didn't find much of interest. So you may have to roll your own to get all those features.

There's a various blogs posts and things detailing such things, such as http://davidgolightly.blogspot.com/2009/02/asynchronous-image-caching-with-iphone.html .

I take it you've considered the Three20 library? I don't think it would cover your requirements though.