There are plenty of resources and videos that demonstrate the awesome power of swift. It is in many ways a lot better than working with Objective-C, it feels more at home like it does when writing Lua code HOWEVER... it is not as forgiving as Lua. So if you are pedantic and use classes, etc rather than the sloppy way of scripts, then you would have a bit of an issue with Swift. The language is easy to use but you have to know the classes and API to really do anything. Since everything is an Object (like in any OO langauge) there are new classes like String and Int which are different to the older ones like NSString and NSInteger, however you might know that the Objective-C API works with CGFloat and not Ints, so be prepared to write lots of conversions between Ints and CGFloats, CGSizes, etc
Playground which is the Live Coding version is fun to work with, specially the graphical environment that displays and attempts to visualise very step the code runs and plot loops, etc. However it is not as fast and would crash more often almost making you wonder are you working with a Mac OS or Windows. With this Apple have now officially managed to make software that crashes as much or more than Windows software does.
Read up on Swift and look out for books, tutorials, video how-to, there are a lot of people that are offering these. Not sure how soon can we see this being adopted as main stream and/or allowing Gideros exported projects to use Swift as the C++ bridge/interface is not easy, you almost have to go Swift->Objective-C->C++.