I found out how to build your apps completely in Xcode 4.3 - 4.5 under Lion OSX 1. Download and set up the files from the repository and install the MIOS32 toolchain on the Mac. That is point 1 and 2 http://www.midibox.org/dokuwiki/doku.php?id=macos_mios32_toolchain_core 2. Launch Xcode. Go to Xcode/ Preferences / Downloads. Download and install Command Line Tools 3. Start a new project based on the 'empty' template. Add some files to the project. From the Project Explorer (cmd 1