title: iPhone memory management, making my app crashproof for multiple devices
body: <p>I'm developing an app which uses a UIScrollView to show a list of images based on search criteria. Using a button the user can load more images.</p>
  
  <p>When testing on an iPhone 4 the ViewController receives a memory-warning at ~750 images. When testing on an iPod 2nd generation a memory warning is received at ~150 images.</p>
  
  <p>My understanding is that when didReceiveMemoryWarning is called, one can free memory by releasing objects but recovery from low memory is not guaranteed.</p>
  
  <p>I've implemented didReceiveMemoryWarning and release basically all objects. In instruments I see memory usage drop back to ~3MB. The first time the iPod reaches its memory limit all goes well, memory is released and the app resumes normal operation. The second time however, when didReceiveMemoryWarning is called, I can see the objects released, but the app crashes anyway.</p>
  
  <p>So, how do I make my app crash proof? I want to make sure that all devices running the app can load as much images as memory allows but I also want to make sure that the app doesn't crash.</p>
  
  <p>I would prefer the app never to reach didReceiveMemoryWarning and set a limit to the number of images that can be displayed, but how can I determine how many images each possible device should be able to load?</p>
  
  <p>Furthermore, the size of the images is not guaranteed. While testing I come to this arbitrary number of 150 on an iPod, but what if the images on the server at some point in time are twice as big? Then the app would probably crash at 75 images.</p>
  
  <p>Any sugestions?</p>