Swift - how to implement completion handler with trailing closure?

Question

Suppose I have function that does some stuff

func doSomethingAwesome(completion:(success:Bool) -> Bool) {

//some stuff

}

How can I transform it to trailing closure ? How can I transform control from body of function to completion block ?

I don't quite understand your question. What you're showing is a function implementation that takes a closure parameter. "Trailing closure syntax" is a shorthand notation that applies to the invocation of the function. This function can be invoked using trailing closure syntax. Beyond that, I'm not sure what you're asking — Alexander
– Alexander, Commented Jun 20, 2016 at 12:37

Yury · Accepted Answer · 2016-06-20 12:38:44Z

1

It is already trailing closure. You can call completion in body:

func doSomethingAwesome(completion:(success:Bool) -> Bool) {

    //some stuff
    let result = completion(success: true)
}

And thats how you can use trailing closure syntax calling this func:

doSomethingAwesome {
        success in
        return success
    }

answered Jun 20, 2016 at 12:38

Yury

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Comments

score 0 · Accepted Answer · 2016-06-20 13:06:08Z

0

You can just call that function (which already has a trailing closure) by doing:

doSomethingAwesome{ finished in

    if finished{
          return true
    }
return false
}

Your completion handler is of type Bool. So Bool is used as I showed here.

answered Jun 20, 2016 at 12:40

user5654610

Your code will not compile: you passed Bool -> Void closure.

Edited. Thanks! :)

will not compile again =) you used unresolved identifiers, use true/false instead

Done! Thanks! Again!