Can one write an add-on or an app that will add a new keyboard layout to iPhone, iPad?
I couldn’t find any reference on the web to suggest either it’s not possible or it’s possible. But because of this my gut feeling was that it wasn’t, but then I came across an app that claims to add Persian keyboard on iPad:
http://iphone.appmobilize.com/apps/172190/persisch-persian-keyboard-for-the-ipad
and:
http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?mt=8&ign-lr=Lockup_r2c1&id=359932063
You can not develop an add-on that will run outside of your app for iOS devices running the stock OS. A security sandbox will prevent that from working. An app can always create for itself a slide-up view containing a work-alike set of buttons that looks like a keyboard, but with any layout you’d like.