_> I don't appear to have a memory leak here so I'm not sure why my address space limit would keep accumulating as I continue scrolling the table view. _
Looks like the returned UIImages (created with the CGImages) need to be released. They UIImages are stored in a NSCache. Unfortunately NSCache is not automatically removing objects when malloc_error_break is hit. The operating system isn't sending my app a memory warning either. I was under the impression NSCache would remove objects at the appropriate time based on certain OS conditions (like this one) automatically. I guess I should be able to resolve this by setting a count limit on the cache and/or manually emptying the cache when CGImageSourceCreateThumbnailAtIndex returns NULL. After manually emptying the cache of UIImages I'm able to load more without getting another cannot allocate memory error.