With Xcode 4 you can develop applications for iPad and iPhone. Also, you can choose a different iOS target. Currently, the last release of iOS is 4.3 and when you will create a new project you will see:

Now, the rootViewController property has been added with iOS 4. This mean that when we going to test the application in iOS 3.2 environment we will get a CRASH! Instead to check the iOS version, we can use a feature of Obejctve-C in order to check if a property exists:

As usual, please don’t hesitate to leave any questions or comments in the feed below, and I’ll aim to respond to each of them.