CODEWITHSUNDEEP
swiftfunctionreturn-type
Alexey Savchenko
Alexey Savchenko

Reputation: 889

Swift function with Void return type versus no return type

I'm struggling with understanding return values in Swift. Can you explain the difference between these?

func someFunc() -> Void {}
func someFunc() {}

Upvotes: 16

Views: 17605

Answers (2)

Adas Lesniak
Adas Lesniak

Reputation: 127

It's just some internal Swift inconsistency. Both definitions define the same, but:

func a() -> () {}
func b() {}          //by  default has same signature as a
func c() -> Void {}  //has different signature than a && b

so:

var x:(() -> Void) = c //OK
var y:(() -> ()) = a //OK
var z:(() -> ()) = c //ERROR - different signatures even if they mean the same
x = a //ERROR - different signatures, can't convert "() -> Void" into "() -> ()"

Upvotes: 4

Ozgur Vatansever
Ozgur Vatansever

Reputation: 52213

Simply, there is no difference. -> Void is just an explicit way of saying that the function returns no value.

From docs:

Functions without a defined return type return a special value of type Void. This is simply an empty tuple, in effect a tuple with zero elements, which can be written as ().

Thus, these three function declarations below are same:

func someFunc() {}
func someFunc() -> Void {}
func someFunc() -> () {}

Upvotes: 26

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