CODEWITHSUNDEEP
closuresswift
rideintothesun
rideintothesun

Reputation: 1678

How to call a closure passed into a function?

I suspect I am missing something really obviously wrong here, so forgive me if I am being a bit thick.

All the examples I see for closures are for passing a closure to the array map function. I want to write my own function which takes a closure

This is what I am attempting 

func closureExample(numberToMultiply : Int, myClosure : (multiply : Int) -> Int) -> Int
{
    // This gets a compiler error because it says myClosure is not an Int
    // I was expecting this to do was to invoke myClosure and return an Int which
    // would get multiplied by the numberToMultiply variable and then returned
    return numberToMultiply * myClosure
}

I am completely stumped on what I am doing wrong

Please help!!

Upvotes: 1

Views: 798

Answers (2)

Alex Wayne
Alex Wayne

Reputation: 186984

Same way you call any function, with ().

return numberToMultiply * myClosure(multiply: anInteger)

A working example:

func closureExample(numberToMultiply : Int, myClosure : (multiply : Int) -> Int) -> Int {
    return numberToMultiply * myClosure(multiply: 2)
}

closureExample(10, { num in
    return 2*num
}) // 40

Upvotes: 2

Nate Cook
Nate Cook

Reputation: 93276

You treat a closure parameter just like a function named with the parameter's name. myClosure is the closure that needs to operate on numberToMultiply, so you want:

return myClosure(numberToMultiply)

That will pass numberToMultiply to your closure, and return the return value.

Upvotes: 1

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