Brent Simmons has a good post about the pros and cons of bringing UIKit to the Mac. On the differences between iOS and Mac development, though, one point did stand out for me:
And there are things Macs don’t have at all — navigation controllers, for instance, since they don’t make sense in a context where you can just show the hierarchy via multiple panes.
Brent’s right that most Mac apps don’t need navigation controllers. I don’t think I’d have any use for them in my Mac app, Clipstart, for example. But navigation controllers are becoming more common in Mac apps, starting with Twitter apps especially. I expect an important part of Iconfactory’s work on the Chameleon framework to bring Twitterrific to the Mac was supporting navigation controllers.
I’ll always consider myself a Mac developer first, even though most of what I do these days is on iOS and for the web. I’d definitely welcome UIKit for Mac. I’m getting closer to announcing a new iPhone app and web platform, and while I have a Mac version in development too, I can’t justify the time right now to finish it. UIKit for Mac would make that decision much easier.