I need an external mic for filming movies with many people.

I am using imovie to make a short film but i want it to sound profesional. The built in mic on the ipad mini and ipod just are not good for what I am trying to do . I need a mic that will get better audio, cut out the wind and one that is like a boom mic that someone can hold over the crowd and will connect to the ipad with a cord. I was thinking of maybe getting the Apogee, but i dont know if you can have an extending cord for it, or if it is good for filming far away audio for a group of people speaking. I was going to get the Irig, but many people said it was very bad so i am stuck on what to use.