CODEWITHSUNDEEP
iosswiftnetwork-programmingalamofirecompletionhandler
mahib
mahib

Reputation: 3

Difficulty with Swift/Alamofire Completion Handlers

Today I am using Alamofire to extract an int value. It's pulling the int fine, but I want to save the int value outside of the request (in a different function, viewDidLoad()).

I'm not sure how to call the completion handler, it doesn't seem to be doing anything at the moment.

Here is the method that extracts the int value in question (lastModified). 

func checkVersion(completion: @escaping (Int) -> Void) {
    Alamofire.request(versionCheckEndpoint).responseJSON { response in
        if(response.result.value != nil) {
            let json = JSON(response.result.value!)
            self.s3Endpoint = json["s3BucketURL"].stringValue
            let lastModified = json["lastModified"].intValue
            self.latestVersion = lastModified
        }
    }
}

I tried saving the value to an instance variable, this doesn't work.

I called the completion handler like this in viewDidLoad().. but I'm positive it's nowhere near correct: 

 self.checkVersion() { response in
        self.latestVersion = response
    }

Can anyone give me some insight on how I can save the int value for lastModified to some local variable so it is not contained within the scope of the Alamofire request?

Upvotes: 0

Views: 1374

Answers (1)

zombie
zombie

Reputation: 5259

In the function checkVersion the completion block isn't called.

You must call it after retrieving the value (although I would suggest to make it optional)

func checkVersion(_ completion: @escaping (Int?) -> Void) {
    Alamofire.request(versionCheckEndpoint).responseJSON { response in

        guard let value = response.result.value else {
            completion(nil)
            return
        }

        let json = JSON(value)
        self.s3Endpoint = json["s3BucketURL"].stringValue
        let lastModified = json["lastModified"].intValue

        completion(lastModified)
    }
}

And call it like this:

self.checkVersion() { value in

    guard let value = value else {
        //handle invalid values here
        return
    }

    latestVersion = value
    // update the view if needed
}

Upvotes: 1

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