So I\'m horribly confused by this error, other threads on Stack Overflow mention I should set the SDK, but I see no option to do this. I\'m trying to build:http://wafflesoftwar
Ran into the same error message ("The selected run destination is not valid for this action") when attempting to use XCode 4 to build/run a tiny Objective-C "Hello, World" project I created in XCode 3.x. Fixed it by choosing to "Manage Schemes..." from the drop-down menu to the right of the Stop button, deleting the one scheme on the list (click checkbox beside the scheme, then click the "-" button at the bottom left), and then clicking "Autocreate Schemes Now".
I also needed to change the "Base SDK" from 10.5 to 10.6, by clicking on 'folder' icon (beneath the Run button), clicking the root/top of the tree view below it, clicking on the blue icon below "PROJECT" in the pane just to the right, and then finally, choosing "Latest Mac OS X (Mac OS X 10.6)" to the right of that.