If you desire to jump right in without necessarily learning all of the fundamentals, you can download "Guitar Free with Songs". This app will enable you to perform current songs from various genres. There are free songs included within the app, but many may require in-app purchases. While this app may not provide you with the chord and key knowledge that you'll need in the long-run, it will allow you to play some wicked tunes pretty fast!
"Coach Guitar" is another helpful and more precise app. It highlights certain songs as well for a new musician to play. However, It also reflects specifics lessons for beginners in which it breaks down the essentials of guitar growth. They even detail how to hold the guitar and strum and pick accurately. Finger patterns and wrist position will also be covered. The app is free to download from the iTunes store with in-app purchases available as necessary.