In a word, "Yes!" In light of my recent post: Your phone is the key to tripling your efforts in life - I have been mulling over whether music production can be done solely on an iPhone (Android is not there yet). As a way of putting my money where my mouth is, I'm hoping to prove that it is.
But why not rather consider the iPad?
My theory is that we can triple our time management efforts in life by squeezing those ten minute waits before meetings, or that little walk to a shop during your business day or waiting in your car for your wife to buy new dummies for your kid (I'm doing that now!).
The iPad, while very mobile, is not up for discussion here. It's the compact device like the iPhone that will make our time management more effective. But I will say that the iPad, with the new version of Auria is pretty amazing for music production.
Firstly, GarageBand for iPhone
I have been using GarageBand for iPhone for a while now and it really has grown up!
* New Drummer feature is incredible - choose from various styles, tell the drummer how simple/complex/loud/soft to play, and tell him/her which part of the kit to play on (includes great electronic options) * Instruments with multi-feature tactile piano is very intuitive and versatile * Sample sequencer is easy to use and powerful * Simple but powerful overall * Inter-app audio is very useful allowing you to record through various other softwares for effects or as external instruments
* Inter-app audio cannot be edited after you've recorded the track, it's saved with the effect or instrument processing * Limited editing features and effects on each track, especially the "Record Audio" track
Currently there are many great effects and instrument apps available for iPhone and iPad. Audiobus allows you to connect those apps in a signal chain scenario. So you can have an instrument playing through an effects chain into GarageBand, or you can play or sing through an effects chain and record it.
Unfortunately there is no way of routing your GarageBand track through effects units so you can tweak, for example, your vocal reverb after you have recorded it. But there are ways to work around that, if you want to perfect that lead vocal sound in the mix. But with a little effort, you'll do just fine the way it is.
IK Multimedia: As far as specifically iPhone music is concerned, IK Multimedia is your one stop shop for hardware and software. With an excellent acoustic guitar tone app, multiple electric guitar apps, a vocal app with pitch correction and doubling, you're hard pressed to find a better selection of sounds. Also, they've developed a professional mastering preset app called the Lurssen Mastering Console. Which, after some listening, is quite spectacular, albeit a bit pricey.
AUFX series: AUFX have released a series of independent effects apps to allow you to run your effects chain like you would in Logic or ProTools (although, as mentioned, you won't have them editable after you've recorded). I used their reverb app for about a year as an outboard effect at live shows, and it worked incredibly well. But their sounds really find their voice in the recording space.
JamUp by BIAS Amps: BIAS amps released a basic version of their desktop modelling software called JamUp and JamUp pro. This is also a very good modelling option and rivals IK Multimedia's offering in terms of varied sounds and a great selection of stompboxes.
These are just a few that I find practical, but there are way more apps out there...
Conclusion: It's still not able to replace a desktop studio environment, but it's getting damned close! I will still import to Logic Pro to tweak the Apple Drummer, perfect my vocals and overall mix, but essentially, you could do it all on your phone. The Lurssen Mastering Console, although "pricey" (not in comparison to sending it off to Abbey Road!) is the final nail in the "iPhone can do it all" hypothesis.
The biggest limitation is not being able to tweak effects once you've used them to record an audio track (although GarageBand does have Reverb and Echo available with that capability). You could work around this by buying the mixing console feature in one of the IK Multimedia apps, import your song without the track in question, and then record it there (be it vocals or electric). Once you have a satisfactory take, you could play with the effects until you feel they're sitting well in the mix, and then save that track independently.
All in all, I'd say it's fair to say you can go ahead and start all your audio projects on your phone, and you'd be surprised to see how much of it remains in the final mix. And for new comers to home recording, it's safe to say you should get an audio interface that is iPhone/iPad compatible because it's probably your best starting point.
I am using an up to date iPhone 6 with an iRig PRO to test these apps and features