Does iOS use some mechanism for caching/restoring UIImageView objects?

I'm using a lot of small images that are placed into UIImageView objects. Currently, I'm trying to foresee the problems that might occur later, such as memory warnings, staying in background and etc. My app is quite small - less than 10Mb but still, I'm a little bit concerned. The reason is that I'm not sure how my app will cope with the situation when a lot of UIImageViews are loaded on screen, then app goes to background, and then after a long time comes back. Do I have to reload all on-screen UIImageViews?

I have read that iOS will cope with UIKit data (such as image views) itself when backgrounded. And that I do not need to worry about restoring this though. It would be OK if my UIImageView objects would use PNG image files directly from app directory. But the thing is I'm using spritesheets (files with several images packed inside), then pulling those images with CGImageCreateWithImag开发者_JAVA技巧eInRect, and then passing to UIImageView at some time point. Now, I'm questioning myself, will iOS cache my on-screen UIImageView objects, or do I have manually to reload those UIImageViews when app goes active? I understand that if a lot of apps will be running in background then my backgrounded app might be killed. But I'm worried about the situation when my app will be still alive (in background) but with released UIImageView objects...Please share you knowledge and insights :)

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Current implementation of "background" apps do a complete snapshot of your app memory. Such approach guarantees that app will be restored after complete killing from a memory in unchanged state. This mean that you do not need to do any additional manipulations such as persisting of code-generated images etc to support restoring of the app. UIImageView will not be unloaded automagically if you will not implement a clean-up logic inside of applicationDidReceiveMemoryWarning for UIApplicationDelegate instance. However an auto clean-up logic implemented for cached UIImages loaded thru imageNamed method.