catch2/projects/runners/iTchRunner

* Select Project -> New Target. Select Cocoa Touch -> Application. Click next and name it something like "Unit Tests"
* While the target info is displayed, find: 'User Header Search Paths' and add a path to the Catch folder
* Open the plist file for the target (Unit Test-Info.plist, if you used that name). Delete the entry for "Main nib file base name: MainWindow"
* From the overview drop-down select the new target.
* Add the file Catch/Runner/iTchRunnerMain.mm into your project - but only in the new target
* Write tests (adding files under test into the target as necessary)