BTCTicker is an open source iOS home screen Bitcoin Ticker. BTCTicker displays a live exchange rate from Bitcoin to your choice of currency (any ISO 4217 currency works) on your iOS homescreen using the app icon badge!
BTCTicker also supports several different exchanges, mBTC display, and also allows for push notifications when the exchange rate reaches a high or low value of your choosing. BTCTicker is fully open source, meaning that the code is open to any and all who want to see and tinker with it.
The code can be found on GitHub: https://github.com/jaygreco/BTCTicker