It is a shame because aesthetically Swift is easily the nicest of the modern safe languages, but there have been really odd noises in the community about project leadership that sour things.
You use this construct for unwrapping nullable fields, for example something like this:
guard let httpResult else { return }
Note that you don't need to assign the value to itself in modern Swift. This line takes an optional (httpResult?) and returns early if null. If not, you can use it with strong guarantees that it's not nullable, so no need for ? or ! to unwrap it later in the scope.
It is, when `self` is captured weakly in a closure, and that closure is outliving the instance.
guard let self else { return }
The big problem with swift is “expression has ambiguous type” and “expression took too long to type check”. Those don’t trade in code aesthetics but are problems I’ve never had in another language.
Yet Apple has managed to create WatchOS. I don’t know what is the portion of Swift, however.