How to use if and switch as expressions in Swift

Swift 5.9's SE-0380 lets if and switch statements produce values directly when assigning to a variable, declaring one, or returning from a function, eliminating common var-then-assign boilerplate and awkward ternary chains. Key rules: each branch must be a single expression (with an exception for branches that throw or never return), an if expression requires an else, and branches are type checked independently rather than inferring a common type like the ternary operator does — so mixing an Int literal and a Double literal across branches fails without an explicit type annotation. The feature is scoped narrowly: it cannot be used as a function argument, sub-expression, or method receiver, and it doesn't change how result builders like SwiftUI's body handle if/switch.

Nguồn: https://sarunw.com/posts/if-and-switch-expressions. 8 Sync News chỉ tóm tắt và dẫn link; bản quyền nội dung thuộc tác giả và nguồn gốc.