App Crashes on iOS 4 (Tracking down iOS 5 code)

I have an app that I am developing and I have a user that reports that the app crashes on iOS 4. I don't have any devices that have iOS 4 on them and I suspect I have inadvertently used some code that is only available on iOS 5. Does anyone have any good tricks for tracking something like this down?

EDIT: I should also mention that the code in question is probably hanging out in the MediaPlayer Framework, so testing in the simulator won't help.

 

If only that were true. I have set the minimum iOS version set to 4.0, but as the SDK is iOS 5 it won't give any warnings or errors (nor do I even have the iOS 4 SDK available).

 

Great link I'll have to hold onto those images.

I do have users with iOS 4 on ad hoc builds. I was just looking for a way to track down the offending code without having a device in my hands (short of double checking every function against the docs). Your point is well taken however, and I've already been tracking eBay for a cheap 2nd gen iPod Touch.

 

Not yet, rather than asking for help on this specific bug I was wondering if there was a nice little trick anyone used to track down this general problem. That problem being, targeting an older OS version and inadvertently including new code.

Incidentally I did stumble on the bug, it wasn't directly in the MediaPlayer framework, but amidst a lot of MediaPlayer code. It turns out I had some generated Core Data classes using scalers for numerical values, which of course iOS 4 doesn't know how to do with @dynamic.

 

Thanks for all the tips guys!

 

And almost a year later I now have problems with iOS 6 code in an app that I want to support iOS 5. A google search pretty much only turned up this thread. I wish there was a better way to deal with this!