Swift 3.1, a limited-focus upgrade to Apple's general purpose systems language, is due next spring, with a few enhancements to the language itself as well as to the Swift Package Manager and Swift on Linux. Source compatibility with Swift 3.0 also is a key goal.
Apple detailed goals for the language in a recent bulletin, but the company already is looking past this upgrade to Swift 4, which is planned for late 2017, according to Apple's Ted Kremenek, release manager for Swift 3.1.
"To meet this goal, Swift 3.1 will include changes in mainline development, i.e. the master branch, only until January 16," Kremenek said. "After that date, there will be a 'bake' period in which only select, critical fixes will go into the swift-3.1-branch and move master on to Swift 4 development."
He emphasized source compatibility as critical to version 3.1. "It is a strong goal that the vast majority of sources that [are] built with the Swift 3.0 compiler continue to build with the Swift 3.1 compiler. The exception will be bug fixes to the compiler that cause it to reject code that should never have been accepted in the first place. These cases should be relatively rare in practice." Swift 3.1 also will get compiler and standard library improvements.
Daily downloadable snapshots of Swift 3.1 release branch will be available; these snapshots will be produced as part of continuous integration testing. "The cadence of downloadable snapshots will thus be more frequent and granular. Snapshots will be posted daily, assuming tests are passing," Kremenek said.
Swift debuted as a modernized follow-up to the Objective-C language in June 2014.