"For KGS you need to use some VNC client (probably the best solution is to use AlwaysOnPC app - details below)
KGS is an unlikely option since William Shubert has generally discouraged clients other than CGoban. William stated that he won't start developing an iPhone version of CGoban until iPhone supports Java applications. Apple has no plan to add Java support, and it is unlikely they will ever support it. Yet, on Lifein19x19 William Shubert stated in Septembre 2011 that his next big project is an HTML client for KGS. This kind of client would work in Mobile Safari on the iPhone. However, no time was specified by wms, and we should assume it will be quite a while.
Currently jailbroken iPhones can install java, however there are issues with the implementation of classpath.
The author of SmartGo has explained in a topic on godiscussions forum that the first version of SmartGo for iPhone does not include an IGS client. More than a year later, there is still no plan for an IGS client in SmartGo for iPhone. Maybe Tetsuki made the author of SmartGo refrain from including an IGS client.
Playing on KGS indirectly on the iPad and iPhone
It is possible to play on KGS without any problems (even if the interface can be difficult to use) over VNC through your home machine. This is accomplished by connecting with one of the VNC clients available on App Store.
A configuration example (this is just an example, there might be a better and/or cheaper options for your platform):
TightVNC (Open Source and Free Software) on my OpenBSD-server. Could as well be running on any normal Windows PC connected to the Internet with the VNC port open/port forwarding enabled in your firewall. (More info on [www.portforward.com
Jaadu on the iPhone.
AlwaysOnPC app. You don't need to have your home computer turned on to play on KGS. There is AlwaysOnPC app. It works like mentioned above but you are connecting to external Linux based desktop with Java&Flash installed. It is far better than using your home computer and leaving it turned on while you are out. Also you get there 2GB of space for your own. I suggest to try out a free desktop client to verify and decide if this is ok for you before you pay for the app.
This way you also get disconnect redundancy since even if your iPhone get temporarily disconnected, you can still just reconnect and CGoban will have continued running as if you had just walked away from the keyboard.
Performance and response over 3G/Wi-Fi is perfect and snappy, but of course depends on your home connection. When running over Edge it's not equally quick, but still perfectly playable."