CODEWITHSUNDEEP
swiftclosures
user7880059
user7880059

Reputation:

Marking a variadic closure parameter as escaping

Assuming a @nonescaping variadic closure parameter as in

func method(_ closures: () -> Void...)

then mutating it to @escaping as in

func method(_ closures: @escaping () -> Void...)

produces the following error.

@escaping attribute may only be used in function parameter position

Upvotes: 2

Views: 367

Answers (1)

rob mayoff
rob mayoff

Reputation: 386038

You don't need to use @escaping here at all. Only a closure that is directly an argument (with nothing wrapping it) can be non-escaping.

A closure that is part of a variadic argument is (under the hood) wrapped in an Array, so it is already implicitly @escaping.

For example, this compiles and runs just fine:

class MyObject {

    var closures: [() -> ()] = []

    func add(_ closures: () -> () ...) {
        self.closures += closures
    }

    func run() {
        for closure in closures { closure() }
    }

}

let object = MyObject()
object.add({ print("first") }, { print("second") })
object.run()

Upvotes: 4

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