Great beginning!

This is a fantastic idea for an app, and I am glad its freeware! Some points for improvement:
1. The user interface needs to be more user friendly. For instance, trying to lock the frequency at a certain point almost always ends up affecting/moving the reception slider bar instead.
2. There should be a recording function.
3. The sound should play even when the app is minimized.
4. There ought to be an official front end that can be purchased separately for this app. It should be pre-built, tested for use with idevices, and should include an antenna. A separate antenna with a ferrite rod should be optional for good AM reception.

Keep up the good work!

SignalRanger1 about iSDR