xCode and pyObjc "build and run"
For those of us who live with pyobjc's xcode templates, there is an annoying little bug when creating a new project, at least on my machines. There are no executables created when you make a new python/cocoa project of any kind which causes xCode to disable "build and run" button. Sure, we can build in Xcode, navigate to the build directory, and run the application, but that's what the "build and run" button is for! How do we fix this? Add the project executable to the Executables group in xcode!
In your xCode session, there is a pane down the left side that shows the contents of the project. In that pane, ctrl-click the "Executables" group, select "Add," then "New Custom Executable". Put the name of your application appended by .app in the "Executable Name field." (i.e. if your app is called "Trigger," put "Trigger.app" in this field). Use the "choose" button to navigate to your application's build directory on your hard disk and choose your application bundle. (If it doesn't exist, try building your application with the build button once first.) Now in the "Project" menu of xCode, "Set Active Executable" to your application name. This should enable the "build and run" button.
UPDATE: Once you've done that ^, you can then change the path to the executable to $BUILT_PRODUCTS_DIR/YourApplicationNameHere.app so that your project doesn't have any hard-coded paths.