This demo project illustrates TDD in implementing a Tic Tac Toe game.
Tap on the board wherever you want to put X or O. You can manually select which side you want to play using buttons at the bottom corners if you so wish, but the selection will switch automatically with each move. To reset the game tap the icon in the top right corner.
To run the app open the project in XCode and hit Cmd+R. To run the unit tests hit Cmd+U in XCode.