OK I’ve seen a few different mobile studio’s, some I posted, some I didn’t, but This FL Studio App that’s coming to iOS(originally only good with Windows) seems like the Producer’s choice, Hit the Jump.
@TatWZA

App includes a 128-track sequencer, step sequencer for individual MIDI clips, a mess of drum loops, reverb, delay, equalizer, amp, and filter effects. With the ability to transport your project file from your iPhone/iPad to your desktop(still Windows though )Clean!