This content was released on Sep 27 2018. The official support period is 6-months from this date.
Swift 4.2 added a lot of polish that can affect your day-to-day coding. This screencast covers some of them.
This is a companion discussion topic for the original entry at https://www.kodeco.com/7752-what-s-new-in-swift-4-2-miscellaneous-changes