StudioMini https://en.wikipedia.org/wiki/StudioMini is a very nice entry level multitrack recorder for iPhone (and there is an XL version for iPad too), but it has the serious drawback that it has no way to share projects.
Moreover, there is no simple way to archive your projects, and if you never make backups of your iPhone you are living dangerously, and at some point your memory will be full with good ideas you cannot export.
Probably needless to say, the author is speaking not about himself but about a band member here.
studiominiscrape is intended to first and foremost get all audio tracks from the iPhone through the web interface.
Eventually it will be able to create Garageband projects from the songs.