Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
Lack of groovebox type apps for ios?
I know there are tons of synth apps- but my sense is that there is a real lack of groovebox type apps- certainly relative to the amount of other apps out there. I am talking here about multi track- including drums and synths- and all with a built in sequencer- ( or even a decent synth with a built in sequencer).
I mean does Korg Gadget have a serious rival? I am aware of some but most with some shortcomings (for me). Here are the main ones I am aware of:-
Caustic- OK- but seems to have been left by the owners- 3.2 promised for months- but no show.
Rebirth- the best of the 303 emulators- but I use my TB3 for all of this type of thing- and it is certainly much better than Rebirth.
Korg iDS 10 & iMS20- fine but I find them a bit frustrating.
Zillidrone- some good sounds- but a bit of a fiddle.
Oscilab- ???- again I'm sure it's just me but I shut this down within minutes of opening it- it's too much effort. 
Figure & iMaschine- OK but not enough sound warping capabilities.
Anyway I'm running out of ideas now. But am I right in saying that there is not too many stellar options? I am sure I have missed a few out- Could you please make me aware of any good ones- not iPolysix either though 
.... or Magellan- whats that sequencer about?
I am aware that this is all probably down to a lack of talent- but I just would like more of this type of app to have some fun with- the more straightforward and obvious sequencer the better (like Gadget)
I actually think that it is possible Korg may have several updates and improvements to Gadget that they are keeping up their sleeve- until some serious competition comes around..... then it will be time to introduce the Master Kaoss Pad or lush sounding multi timbral Gadget or some Randomize features or whatever..... that latest update was a bit of a damp squib. I would wager that Novation will be sniffing around this type of scenario (at least I hope they are) 
Comments
Tabletop is awesome but not very reliable, you'll probably run into some issues, the main one for me is it wont save iProphet properly. But it's still awesome. IMO.
Glitch breaks? (…which also supports link now).
Mint.io
GM Groove
@robosardine Caustic is definitely not abandoned - update on the way. Others could be RD4, Mint.io, Stroke Machine, WeJaam etc., but actually with virtual MIDI, background audio, IAA, AB and AU supported by apps such as AUM and Modstep then you can actually think of your iOS device (iPad) as a groovebox unit.
My favorite kinds of apps. When done well, they allow you to get into a completely unhindered and fun musical creative flow, when done poorly they become just another daw whose functions you have to wrestle with. Until Someone can do better, I would still say the Korg ikaossilator is the best pure groove box type app. Certainly NOT due to its sound sculpting abilities of which there are none, but the way the workflow is designed. Takes full advantage of the strengths of touch point recording and building a song is as simple as get a loop going, save it, change it, save it again, change it again, and then lo and behold all your variations are saved in the arranger and you never had to pause the music. Really hoping Korg is going to incorporate some of that into gadget or vice versa, particularly the Kaoss pad and save system.
Caustic will be worth the wait. I'm running the beta now. I'd like to see something like the old Quasimidi 309.
triq traq is absolutely terrific
Think it depends on what you mean by a groove box—what about Gadget keeps it off your groove box list?
Lots of good suggestions above already (definitely check out triq traq). I'll add Nanoloop if you like 8-bit chippy stuff. Caustic and Nanostudio are great but feel a little more open ended than the way I think of groove boxes. Cotracks? iSequenceHD?
Magellan's sequencer is more like an old school step sequencer.
I love Gadget, but I wouldn't class it as a groove box due to its sequencer being too DAW-like. No bad thing, though I find it lacks a certain immediacy I'm getting from stuff with simpler step-based sequencers. At least, I work very differently in Gadget compared to say even iDS-10. Variety is the spice of life, but if Gadget were to add an optional step sequencer mode I think I'd be in hog heaven.
I recently picked up iMaschine 2, and I do like it (the expansion packs are excellent, lots of inspiration within), though I think it's perhaps too simple, it needs some automatable sample bending controls stat, fx send levels, and a step sequencer for the keys (I don't mind playing live, but my timing is crap and the lack of facilities to correct mistakes outside the quantize catchment zones is leading to some serious amounts of repetition! ). Oh and more than a mere 4 patterns for each track, 8 would be enough.
Keep an eye on Skram
Gotcha. Beathawk? Maybe one of the Amidio (sp?) apps?
This!
I have been doing this lately
Sequencing synths from fugue machine, patterning or modstep,
Then with link either tracking it out into live or sampling into my mpc or or even into impc pro or whatever
But yeah your iPad is a super deep grovebox of its own, with some glitches when apps decide they don't like each other lol!
Modstep (far and away the best)
Stroke Machine. Make drum and synth patches with sample, synthesis or both...really a blast, live and otherwise.
Image Line Groove Machine Mobile. Very capable and underrated.
Oscilab is worth the time to dig in.
I don't play with this one enough. +1
zMors modular, open end groove box.
Sunvox too
Egoist, while chiefly a slicer is certainly a groovebox to me. The drums are fun and with the bass you can send midi to other synths... In fact add midiflow and midilfos to the mix and you got some crazy magic!
Oh and yes bring on the grooveboxes! Cant wait till Skram gets updated with... anything
Now there's an idea. An iCircuit would be amazing! (Aside from the inevitable screams for 80 more tracks!)
> Oscilab- ???- again I'm sure it's just me but I shut this down within minutes of opening it- it's too much effort. :)Same here, i just bought Oscilab and i can load 2 or 3 synth via AB but it crashes.I don't know If my IPad Air 1 iOS 9 is too weak or If it's an oscilab bug
Waldorf Attack for the same reasons of Stroke Machine. Node beat, Reactable, patterning, SeekBeats are some others not already mentioned.
Actually I never liked that much the groove box approach too much: most of them were/are very complicated(thinking about yamaha's) and programming those things was a pain; thousands of pages accessible with a few buttons, strange way of sequencing and so on.
Are you talking about my QY700 there?
I'd like korg to release a iEMX. That's a super groovebox - 10 drum parts, 5 synth parts
I was thinking of the RS7000
Ah yes, that’s even worse! The QY700 requires the manual beside it every press of a button. When I looked at the RS7000 in a shop once, I could see it was the same, only more.
On the other hand, the other day I did actually do something (primitive) on Yamaha’s Mobile Music Sequencer, which after several years of staring at it (while wistfully remembering my far easier to use QY20) was an achievement. After the nice easy pocket devices, they really did make those things too complicated, and nobody tapped them on the shoulder to tell them.
Modstep is incredibly capable when you get your head around it.
GM Mobile is also really good, very few updates, but it hasn't needed them.
Lack of Grooveboxes on iOS ? You have to be kidding
I'm seriously thinking about pairing ModStep with Roland iOS-Soundcanvas as this would bring me pretty close the MC-303. Still don't own ModStep but those who own it can maybe tell me if it includes a 'preset' for controlling the Soundcanvas (parameters, patch names, drum/percussion maps and a GM/GS mixer).
Korg Gadget is still my favourite 'GrooveBox' on iOS.
@Samu
I can't see a template for Soundcanvas in the list.
You can create your own templates though which wouldn't be too difficult if you have the Soundcanvas midi implementation chart
I was just thinking since GM/GS/XG has been around for like ages I just assumed it would be included from start. Program/bank change can be sent but there is no support for 'patch-lists' or 'drum-maps' but thats something I can live with.
It would be amazing to see Roland re-vive the 'GrooveBox' on iOS and update it with sampling support
Me too, but I cannot find it in the list.
Drum-maps of a sort are supported within ModStep when using a drum track as opposed to a melody track, you set the input and output note of a pad to allow using different setups for different drum machines without need for changing all the midi, just the pad mapping.