How to test if your iOS app behaves well on memory warnings?

Question

I recently noticed that sometimes our app crashes right after receiving a memory warning. It's very hard to reproduce this problem on device, and even in simulator I get this crash in maybe one of ten attempts to “Simulate Memory Warning”.

What is a good strategy to debug memory warning handlers, considering issues often come from callbacks arriving “too late”, resources accidentally used after being destroyed in warning handler, etc?

Answer 1

Here's an approach that helped me find several severe bugs in my memory warning handlers.

First, I went to OS X Keyboard settings and assigned a shortcut to Simulate Memory Warning:

Then, when running the app in simulator, I kept these buttons pressed, so the Simulator would generate tens of memory warnings per second. While doing that, I would go around the app. Of course this is rarely what happens in the real world, but this stress-testing helped reveal some synchronization, callback and state issues, which I wouldn't have found otherwise.