Some sample code from my iOS game Sling Ball.
Sling Ball's Description:
Sling Ball is an explosion-packed infinite climber! You'll need quick reflexes to escape the climbing lava, dodge the mines, avoid the missiles and collect as many coins as you can! There are also power-ups, coin clusters and daily challenges to help you earn coins as fast as possible! Once you have enough coins you can spend them on loads of new balls by unlocking and smashing open a Pod.
AppStore Link: https://itunes.apple.com/gb/app/sling-ball/id1442402440?mt=8