ipad memory issue loading images in UIWebView

I've got an issue similar to this one: iPad/iPhone browser crashing when loading images in Javascript

... but I'd like to clarify that my issue is caused by the same memory issue, and if so, what I can do about it.

I understand the proposed workaround of loading "tiny.gif" images for img elements that aren't in view, but the thing is, I'm not using loads of img elements. I'm using four. Three in a sliding div that slides in the next/prev image, and one that displays the current image while the sliding div is doing its sliding thing. It's a little hard to explain the mechanism, but the point is, there's only four image elements and I'm just continually swapping their src.

So what I don't get is.. if there's only four img elements in memory, how am I running up against the memory issue? If slide_one is an image with a src of one.jpg, and I change its src to two.jpg, surely one.jpg is cleaned out of memory, right?

Just a little background: I'm running a HTML page through a UIWebView as an iPad app. The behaviour I'm seeing is that I can load about 25 of these roughly-250kb-per-image JPEGs, and then it stops loading them (the src attribute is updated but the image stays blatantly unchanged). This sounds suspiciously similar to the 6MB limit I've heard mentioned, but I'm n开发者_JAVA技巧ot seeing any warning or crash (at least, not in the iPhone Simulator where I'm debugging this).

Any advice gratefully received... :)

FWIW, I solved this by swapping bg image on the containing div rather than using an img element and swapping its src.

So either it's a bug that memory management doesn't allow more than x MB of images loaded, or it's a bug that bg images don't count towards that total.

Ho-hum.