Since heightForRowAtIndexPath is called before cellForRowAtIndexPath, I was assuming that if I wanted to modify the height from within cellForRowAtIndexPath, I could do so. It seems I can't. I've tested via NSLog and if I change cell.frame.size.height, the change is stored in there properly, but the cell itself doesn't take on the new size (it's using the one I set in heightForRowAtIndexPath).
Is there another method that would adjust the cell's height that's called at some point after cellForRowAtIndexPath? If not, is there another way around this? I need to use cellForRowAtIndexPath since I'm deciding on the fly whether to randomly add an image to each cell in turn.
You should put the code that randomly decides to add an image in your heightForRowAtIndexPath method instead.
Use a NSMutableDictionary to keep track of the NSIndexPath's that use images.