tableView: update individual rows when threaded loading of individual images is complete

I guess you’ve all seen it: a tableview with thumbnails, showing title and subtitle instantly, but with the thumbnails popping up as they are loaded afterwards.

So: Lazy loading of images. I’ve done this before on Iphone in Obj-C, in the Ramudden app.

I receive a JSON file with title, subtitle, and image url that goes into a lua table. No problem.

I would then (in onRowUpdate) like to start a thread that loads each image in turn, and when the image is downloaded, it should swap out some placeholder image for the loaded one.

What’s your best strategy for this? Are there good example to have a gander at?

Primarily I need help with thread handling and force-updating and rerendering of the rows, the rest I should be able to figure out.