How do I determine which iOS SDK I have?

Question

I\'m sure this is simple, but how do I determine which version of the iOS SDK I currently have installed?

Answer 1

Update: Thanks to Stan for showing how to do it with Xcode 4.3 on Lion:

ls /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/‌​SDKs/

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The following command shows a listing of all the iPhone SDKs installed on your computer.

ls /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/