MacOS app does not run on the Xcode simulator

Question

I\'ve installed Xcode 4.2.1 on Mac OS X Lion.

When I create a new (Mac OS X Cocoa) project and I click \"Run\", Xcode says build succeeded, but does

Answer 1

Simple

Select the desired active scheme and device/simulator from the toolbar (next to the "play" and "stop" buttons).

The scheme selection should look something like below where the name is that of the appropriate target.