What’s New in Swift 5.1
SE-0068 expands Swift’s use of
Selfso that it refers to the containing type when used inside classes, structs, and enums. This is particularly useful for dynamic types, where the exact type of something needs to be determined at runtime.[…]
In Swift 5.1 this confusion now prints a warning: “Assuming you mean ‘Optional.none’; did you mean ‘BorderStyle.none’ instead?” This avoids the source compatibility breakage of an error, but at least informs developers that their code might not quite mean what they thought.
[…]
Well, in Swift 5.1 we can now use switch/case pattern matching to match optional enums with non-optionals, like this[…]
[…]
SE-0240 introduces the ability to calculate and apply the differences between ordered collections. This could prove particularly interesting for developers who have complex collections in table views, where they want to add and remove lots of items smoothly using animations.
Or for use in test cases.
Because Swift now ships inside Apple’s operating systems, new features like this one must be used with an
#availablecheck to make sure the code is being run on an OS that includes the new functionality. For features that will land in an unknown, unannounced operating system shipping at some point in the future, a special version number of “9999” is used to mean “we don’t know what the actual number is just yet.”
