Xcode Only Gives Me Desktop Architectures for iOS App

I have an iOS project that I've put in Dropbox to work with a few friends. The issue is that it seems to get "corrupted", so that after some time (after someon开发者_C百科e else has accessed the Xcode project file), when I try to go and open it again I get a Base SDK Missing error. In the Project Settings, I discover that I'm missing the valid ARM6/ARM7 architecture for iOS apps—I can only choose from 32-bit or 64-bit Intel. My only other options are i386, various forms of PPC, and x86_64. I simply can't build for iOS anymore.

No one else that I'm working with seems to have this problem. It exists in both Xcode 3 and 4, so it's not an Xcode 4 issue either.

Is anyone else having this problem? Is there a fix?

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In these cases it's often a good idea to 'Clean All Targets'. I have found that particularly after upgrades to XCode where platforms or architectures have changed, that XCode can become confused about the state of previous builds. Cleaning, then re-specifying your desired targets/architectures/etc and then rebuilding will work well.

Also don't forget that if you hold Alt (or Option) down when you click on the Active build settings drop down will give you additional options.

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Can you reinstall XCode? Also, it might be wiser to host the project under source control.

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Hehe...turns out that the project had been used under the 4.2 SDK and at the time I only had 4.0, which explained the missing SDK part...Updated to 4.2 and it's all fixed now.

Source control would've been nice, but there aren't that many good ones that support the features we need (for free); if anyone's got a guide to installing Subversion on OS X and using it (without being too technical read Terminal), I'd appreciate that. Or how to set up Git with Xcode 4 (although I know that's under NDA, so that's probably not going to happen).