iPhone App compatibility between different OS versions

Question

Currently, I have an iPhone app published in AppStore. I've developed it using XCode 3.1.4 and compiled it under the iPhone SKD 3.0. At AppStore the application shows 3.0 as the minimum OS required. Everything is fine.

Now, I have downloaded the XCode 3.2.3 and I want to send an update of my app with compatibility for iOS 4. My question is: If set the "iPhone OS Deployment target" to iPhone OS 3.0 and the Base SDK to iPhone Device 4.0 (or iPhone Device 3.2), then when Apple approves my app, what will appear as the minimum OS required? Will my app run on a device that has OS 3.1.3? Will it run on iOS 4.0?

Answer 1

It will appear as 3.0 mimimum and run on everything from 3.0 upwards.

Make sure to test on devices with your supported OS, and make sure you don't call or use any fancy 4.0 stuff on those devices.