Hi, here is a good question:
I have an application compiled for iPhone OS 2.21. When I run this on my iPhone 3G (updated to OS 3.0) the application runs fine. Is this a guarantee it will run on iPhone 3GS?
If I take the same code and compile for 3.0, part of the code do not runs on my iPhone, specially a scroller that does not scrolls... and during the compilation no error is shown. Why?
So, I have these two good questions for you guys! Thanks for any help! :-)
Code compiled for 3.0 will not run on a device with an earlier os.
Code compiled for 2.2.1 should run on 3.0 for the most part. But you are responsible for testing your app to make sure it runs on 3.0.
If it runs on a 3g, then it should run on a 3gs, but ideally you should test on all your target devices to make sure.
I have discovered that it is possible to compile for 3.0 and run on earlier versions. Apple has a sample code on how to do that on their site. I find a little bit risky to do that, specially if you, like me, doesn't have an earlier version of a device to test this on.