I love TouchOSC, it's been consistently reliable and well-supported for years (the developer seems like a nice chap too). I bitched for ages about wanting Lemur to appear in app form, but still haven't bought it since it appeared.

Other apps of note in my 'Music Comm.' folder:

GyrOSC - Gyro/Accel/GPS/Compass data when I need it. Super simple and reliable. Nice devleoper.Beatsurfing - I never properly explored this, but it was fun when I tried it briefly. OSCPhysics - fun, but limited in application I suppose. It looks to be missing from the App Store too.

Also of note is MobMuPlat, which lets you load Pd patches onto your iOS device and create interfaces with a desktop editor. I suppose you could use [netsend] in Pd to talk to Max and program interesting control stuff on there too.

Hey Bas :) At the moment, Lemur... but obv restricted to iPad. Not had any issues with TouchOSC (I have iPad 3 also) - always been stable, but not as feature rich (esp with the 5.0 update) - advantage is cross platform but is generally slower than Lemur. Dipping into Mira which is alot more stable these days, but I think waiting for next update before really diving in...

So, currently Lemur... I think it was you that told me that you could pick up old i devices quite cheap so that's what I'd currently suggest....

Saying that, those are the only 3 options I've currently explored....

I had used the C74 app successfully in the past.

I have one iPad running Lemur to control various parameters in my Max environment --- the actual parameters can change depending on the particular "song" loaded. Typically, they are volume control sliders. The text underneath each slider on the iPad is updated from Max as different songs are loaded so that you can see what each slider represents at any time.

I have tried TouchOSC in the past and I've also played with TB MIDI Stuff which I think has potential as well, but Lemur still beats them both --- it's expensive but worth it if you're doing anything really serious.

I have another iPad running Scorecerer (a sheet music manager, disclaimer, my company makes this) that sends MIDI commands to Max that cause Max to perform actions such as loading different patchers ("songs"). Using pitchbend messages as the underlying representation, page numbers are also sent to Max. Max can also send messages back to that iPad to change the current page. At some point I'd like Scorecerer to generate OSC as well because MIDI requires Network MIDI to be configured every time I set up the computer, which is a bit of a pain.