Swift 2.1
If you thought Apple was slowing down with Swift, think again. Xcode 7.1 Beta 2 includes Swift 2.1. As always you can check the release notes for yourself because I don’t necessarily address everything here.
[…]
If only
privatethings are modified in a file then it does not trigger recompilation of all files that depend on it. In some cases this can have a huge performance benefit[…]
Function/closure types now have covariance and contravariance.
Update (2015-10-14): Russ Bishop covers Swift 2.1 Beta 3.
