This is a small app in Objective C. It basically plays sounds after you select the scales.

You can search by Chord or create your own progression.

CFTreeRef has been used as a DataStructure. The tree is created and then populated in the AppDelegate. Different accessor methods are created to get elements at certain depths.

Its a great intro to CFTreeRef DataStructure if anyone is ever interested in it.

Obviously you can create your own tree data structure from scratch but if Apple provides one why bother re-inventing the wheel.

Also please note this app only runs on iPad.