From my initial research there are many alternatives for add-in, plugg in micros. Some are directly connected to the audio entrance of iPhone, others to lightning port.
Based on a general propose to record audio I was tempt by XY microphones. They are redirectibles and some of them offer a nearly professional quality.
Micreview.com, web site focused on micro testing, made a great list of iPhone devices, which we will check here too. (Thanks guys!)
Review by Sean initially appeared on micreview.com on March 13th 2014
If you know us well, Rode is one of our favorite microphone creators, period. When we heard they were joining the club in iOS mics, we needed to see what it was all about. You most importantly can record up to 24-bit/96k audio quality, giving you the clarity of even most USB microphones out there. The mic has built-in A/D conversion for lighting and 30-pin connectivity. The XY stereo build of the mic in itself is a mechanism we’re fans of — it’s basically two directional mics placed at 90 degrees from each other, with each mic having different sound pressure differences for increased clarity and less “space”. It allows you to capture a relatively wide area of recording.
Besides the great audio quality and mic build, the Rode i-XY comes with quite a few accessories. You get a foam wind shield and protective zip case, which is especially great for those traveling and\or recording out in the field. What’s even better is they have their own recording app, so you’re not forced to use the stock software that comes with iOS. Although it isn’t anything too crazy, it’s a bit more convenient for recording and visualizing your audio. It’s called the Rode Rec app. This is our top pick for our list, albeit a tad bit more expensive than most, you’re getting what you pay for.