Swift Closure Completion Handler

Question

I have a function right now that is determining the hide behavior of a UILabel: func shouldHideLabel() -> Bool.

I need to retrieve data from a web request to determine whether or not to hide this label, so inside of shouldHideLabel() I'm making a call to a function func webRequestDataIsValid() -> Bool.

webRequestDataIsValid() is doing a web request with a closure, returning an object, and the object has a variable isValid on it, which is returning true or false.

My goal is to wait on this isValid flag to be returned to me, return from webRequestDataIsValid with true or false, and then use that return value to return from the original shouldHideLabel function.

I'm using a completion handler inside of shouldHideLabel to wait on the data from webRequestDataIsValid, but I'm not sure how to wait on returning inside of shouldHideLabel for my closure to finish. It seems like you can't return from a function while inside of a closure.

Any help is much appreciated. Thank you!

[Edit] your question to include your actual code. – rmaddy Feb 23 '18 at 16:38 — rmaddy, Feb 23 '18 at 16:38

score 1 · Answer 1 · answered Feb 23 '18 at 16:48

I would assume that your web request will contain a completionBlock, try this:

func webRequestDataIsValid(completion: @escaping ((Bool) ->Void)) {
    whateverYourRequestMethod.response { httpResponse in
        let isValid = true // retrieve your boolean
        completion(isValid)
    )
}

Swift Closure Completion Handler

1 Answers1