Xcode 4 skips coping app to device/simulator

Question

Whenever I attempt to run the debug version of my app, Xcode (4.0) compiles successfully, skips copying and just runs the old version. However if I clean first, Xcode copies just fine...

No relevant warnings, I triple checked the project and target build settings. Skip install is set to NO on main project and targets, all dependency projects have skip install set to YES.

Any ideas would be very welcome, recompiling every run is very painful.

Answer 1

Xcode's Clean command doesn't clean very thoroughly. There's still plenty of derived data retained after cleaning, something of which can cause these symptoms. I've had the same problem happen to me, where it kept running a old version of the app. To fix it I deleted the app from the simulator and deleted the Xcode derived data for the project.

To delete the derived data, quit Xcode. Locate the derived data in your account Library folder (~/Library/Developer/Xcode/DerivedData/), and delete the folder for this problematical project. Reopen the project in Xcode, and build and run.