Ash Furrow with the story of trying to build a new app in Swift over the last few months. This was an ambitious project with a tight deadline, written primarily with the Swift betas and using ReactiveCocoa just in case everything else wasn't cutting edge enough. Great post, worth a read. Also, the app is open source so you can see the finished (and ongoing) result.
You might ask what this article is doing in iOS Dev Weekly but I think this is big news. There are an enormous amount of .NET developers out there and the next version of Visual Studio will have built in support for downloading Xamarin to enable "native" iOS development out of the box. Also, as part of the same announcement it was interesting to see Microsoft open source the .NET framework, including taking contributions. Truly, times have changed.