In the same way that you can pass a closure to a function, you can get closures returned from a function too.
The syntax for this is a bit confusing a first, because it uses ->
twice: once to specify your function’s return value, and a second time to specify your closure’s return value.
To try this out, we’re going to write a travel()
function that accepts no parameters, but returns a closure. The closure that gets returned must be called with a string, and will return nothing.
Here’s how that looks in Swift:
func travel() -> (String) -> Void {
return {
print("I'm going to \($0)")
}
}
We can now call travel()
to get back that closure, then call it as a function:
let result = travel()
result("London")
It’s technically allowable – although really not recommended! – to call the return value from travel()
directly:
let result2 = travel()("London")
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