Xcode is not launching my app for debugging

Question

My iOS project installs fine on the iPhone but the application won't launch automatically for debugging.

I'm using Xcode 4.2 (Build 4C199), the latest version for Snow Leopard (10.6.8).

I've already tried deleting the app from the iPhone, restarting the device, cleaning the project and reinstalled xCode.

Any ideas on how to solve this problem?

Answer 1

In Xcode click on where the project name/Device or simulator version is (On the right of the Stop Button), and select Edit Scheme, on the Run Tab select Build Configuration -> DEBUG, and select a DEBUGGER -> GDB.

Answer 2

In my case, I created a new target and a new scheme by duplicating the existing ones, in order to test my app on devices with on older iOS version.
However, the copied scheme had as executable selected "None":

As soon as I selected the right executable there from the drop-down menu, the app launched.