[saagarjha]

Swift is largely compatible with Objective-C; for your preference pane question the answer will certainly be yes now due to ABI stability and preference panes running out-of-process. I would expect dealing with the Accessibility API to be the more annoying part, and that only because it's a C API working with function pointers, which means you can't use blocks (which is true with Objective-C as well, but generally par for the course when working with interfaces that Apple doesn't care much for).