Total switch from wpf/vb to mac

I'm looking for recommendations, what to use to build graphical user interfaces with such freedom and ease as something like expression blend offers but for mac and apple mobile development.

I will be completely moving away from Microsoft's tech and dedicating all future development to apple hardware and operating systems.

Advise would be appreciated.

Xcode comes with every mac. You have to install it from the Disks.

Check out Apple Developer there is the iOS SDK available there.
Apple Developer