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.

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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.

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