Here are 20 sessions I’m watching from WWDC this year. Naturally, I try to select sessions that I think will have direct impact on my day-to-day work. Because of this, I’ve chosen to mostly skip the Vision Pro-related content for now.
Swift
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- Swift 5.9 allows if/else and switch statements to be used as expressions. This means instead of using ternarys, for example, you can do:
<each Result>type parameter pack. Functions can now take multiple generic arguments, and return a tuple of the matching type results, instead of needing to define new functions for number of arguments.- Macros. Look like functions, but introduced with the
marcokeyword. - Foundation is being rewritten in pure Swift: https://forums.swift.org/t/what-s-next-for-foundation/61939.
- Non-copyable types allow you to mark value types with
~Copyable, which prevents structs from being copied. You can also mark functions asconsuming, which prevents the value from being used after aconsumingmethod is called. - Better C++ support.
- Custom
actorsynchronization.
let x =
if isRoot == 0 { "zero" }
else if isRoot > 0 { "greater then zero" } public macro assert(_ condition: Bool)Freestanding macros can be used anywhere, while attached macros are associated with specific elements in code.
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- When possible, prefer structured concurrency over unstructured. Structured means things like
async letandtaskGroup, where unstructured are plainTask { ... }orTask.detached { ... } - In other words, it’s better to do
async let x = doSomething()instead oflet x = Task { await doSomething() } - Structured tasks are implicitly cancelled when they go out of scope. Unstructured tasks must be cancelled explicitly with
cancel. - Cancellation is a race. Cancelling tasks just sets the
isCancelledflag to true, which means that code will still execute if the task is cancelled too late. - Instead of returning a partial result, you can throw a cancellation error by calling
try Task.checkCancellation() - 8:00 resume
