What is type '()' in swift? -

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• difference between returning void , () in swift closure 3 answers

i'm receiving event passes parameter of type ().

is empty tuple..?

i'm referring type of expression:

let x = ()

() both type (and void type alias empty tuple type) , value of type. so

let x = () 

defines x constant property of type () (aka void) value ().

equivalent statements be

let x:() = () let x:void = () 

but not

let x = void // error: expected member name or constructor call after type name 

because void type not value.

when defining function types no parameters and/or no return value there seems consensus use () empty parameter list, , void no return value. can example seen in uikit completion handlers, or execution blocks submitted gcd dispatch queues, e.g.

func sync(execute block: () -> void)