I found this app a while back called "Maestro - Music Composer". When I found it it was really buggy and was missing some important stuff; but now, after a recent update, it works amazingly and is the best music composer for mobile I have found. You can export to a .mid file and .pdf so you can transfer your work from your phone to your computer with a little bit of work. I find it very useful if I am out and about a lot or even out of town. Here is a link to it in the Play Store (https://play.google.com/store/apps/details?id=com.futuresculptor.maestro).
Thanks for sharing this great app. This is what I'm looking for.