Wavelength

 Wavelength  is an open source iOS app for micro.blog for recording, editing, and publishing microcasts and uses Micropub to post audio to micro.blog.
 * https://github.com/microdotblog/wavelength

Announcement: http://www.manton.org/2018/04/wavelength-for-micro-blog.html

Limitation: can only post to micro.blog for now.