Undo "Upgrade Current Target for iPad?

I've upgraded current Target for iPad and I dodn't like the result. Now, i've tried to downgrade by deleting files but it's not working. Help!

Do I need to change project settings? Does XCode keep a backup of the project? What to do... It doesn't run on iPhone anymore...

EDIT:

The console crash log on the iPhone Simulator:

2010-05-10 00:11:02.455 iDecide[9743:207] Unknown class iDecideAppDelegate in Interface Builder file.
2010-05-10 00:11:02.456 iDecide[9743:207] Unknown class iDe开发者_开发知识库cideViewController in Interface Builder file.
2010-05-10 00:11:02.465 iDecide[9743:207] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UICustomObject 0x391eb80> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key viewController.'
2010-05-10 00:11:02.466 iDecide[9743:207] Stack: (
    34047067,
    2420679945,
    34206145,
    215656,
    214197,
    4551796,
    33949999,
    4546347,
    4554615,
    2715730,
    2754518,
    2743092,
    2725503,
    2752609,
    39038297,
    33831808,
    33827912,
    2719253,
    2756527
)

EDIT:

It seems that I've removed my Class files from the project. It now works on iPhone Simulator again. Time to check out the deal with iPad simulator and the minimum OS.

Look under Targets - you should have your original target and another that is the app name-ipad (or something similar). You won't be needing this target anymore so get rid of it, and make sure your build configuration is pointing at your original target - this way, the correct files are compiled and copied across into the application bundle when you perform a build.

I would recommend that you always have a backup of your project anyway - particularly before you run a tool on your xCode project that makes changes as large as this. In fact, I find it is always worth going that one step further and using source control management.

Xcode has inbuilt support for SVN but I still find it buggy (especially when dealing with resource forks) so recommend using a separate client (I use Syncro). You can even set up your SVN repository locally (on your file system) so don't have to have a designated server/host. There are hundreds of guides on google for SVN so its worth looking into.

SVN gives you a working history of all changes to your project, so you can revert to a working codebase If The Worst Happens. The time lost setting up a source control system more than offsets the time it takes recovering from accidents like you've experienced.

Go to edit active target (edit your deployment target), then change Targeted Device Family to iPhone