Robin Good: If you are looking forward to find the best tools, apps and hardware gear needed to do quality audio recordings for your iPhone-based video shootings, here is an excellent one.
Jeff Geerling has put together a comprehensive resource guide to external microphones and complementarty tools that can be utilized with most iPhone, iPad and iPod models.
If you are just starting with an effort to do quality audio recordings with your iOS device, you will find a ton of useful tools and resources in this guide.
Recommended. Very useful. Resourceful. 8/10
Video clip comparing audio quality of different microphones: http://youtu.be/yJ06qn0czak ;
Via Robin Good, Anca Toader, Blair Cook