iphone app with many images

Do it the simplest way possible first. Do not optimize until you've actually written a program and have actually found it isn't fast enough. You may be surprised and discover that it'll run your simple code fast enough. You might find that it is too slow, but upon profiling you might discover a bottleneck unrelated to your pictures.

 

200 images isn't very many. What is the size of ipa file that's generated?

I've worked on apps with thousands of images. There was very little special done vs other apps. I made sure the images weren't being cached in the image cache, based on my knowledge of how they were being used in the code. I wrote a replacement for pathForResource because profiling showed that it took up some time unnecessarily.