Return value after Alamofire dowloaded data

Question

I have a function that download data using Alamofire and then I would like to return that data. Now I know that Alamofire runs asynchronously and in order to to return data I should use completionHandler, however I don't get it how to use it. Since I am not the first with such problem, I found some solutions to similar problems, yet I am not sure to apply them to my case. Here is my code:

func downloadImageFromServer(imageUrl: String) -> (String, String) {
    var myData1 = String()
    var myData2 = String()
    Alamofire.request(.GET, imageUrl)
        .responseImage { response in
            switch response.result {
            case .Success:
                if let newImage = response.result.value {
                myData1 = //returned image name
                myData2 = //edited image name
                }
            case .Failure:
                //Do something
            }
    }
    return (myData1, myData2)
}

Should I do something like this:

func downloadImageFromServer(imageUrl: String, completionHandler: (String?, String?) -> ()) {
    var myData1 = String()
    var myData2 = String()

    Alamofire.request(.GET, imageUrl)
        .responseImage { response in
            switch response.result {
                //if user does have a photo
            case .Success:
                myData1 = //Something
                myData2 = //Something else
                completionHandler(myData1 as? String, myData2 as? String)
            case .Failure:
                //Print error
            }
    }
}

Update Yes, my question is very similar to that other question, however in my case, code has to return 2 values and that's where I find difficulties. Here's my code for gettin values:

 func getImages(orders: String, completionHandler: (String?, String?) -> ()) {
    justDoIt(orders, completionHandler: completionHandler)
}

and then

getImages(imgURL) { responseObject, error in
    print(responseObject)
    return
}

And it works, however I am able to access only first value of the two, how to access both?

Yes. You could also add variable to completionHandler closure, that will indicate if it is success or error (or you could add errorHandler). — sunshinejr, Dec 22 '15 at 18:52
Good example here: [How to return value from Alamofire](http://stackoverflow.com/questions/27390656/how-to-return-value-from-alamofire) — Eric Aya, Dec 22 '15 at 18:52
@EricD. I've seen that example, my second code is based on that example, however I am not if it's right because I have to return 2 variables. Also since function is returning 2 variables I am not sure how to access them. Although I have an idea — Georgy, Dec 22 '15 at 18:57
@sunshine What about getting data from that function? That seems to be hard part for me — Georgy, Dec 22 '15 at 19:25

sunshinejr · Accepted Answer · 2015-12-22T19:39:05.460

Your approach is correct. You could use another variable in your closure to see if the request was called properly (or another variable in function, e.g. errorHandler). Example of usage:

downloadImageFromServer(imgURL) { (data1, data2) in
    print("Data1: \(data1). Data2: \(data2)")
}

Basic example of adding success/failure variable to your function:

func downloadImageFromServer(imageUrl: String, completionHandler: (Bool, String?, String?) -> ()) {
    var myData1 = String()
    var myData2 = String()

    Alamofire.request(.GET, imageUrl)
        .responseImage { response in
            switch response.result {
                //if user does have a photo
            case .Success:
                myData1 = //Something
                myData2 = //Something else
                completionHandler(true, myData1 as? String, myData2 as? String)
            case .Failure:
                completionHandler(false, nil, nil)
                //Print error
            }
    }
}

Usage of the improved version of downloadImageFromServer():

downloadImageFromServer(imgURL) { (succes, data1, data2) in
    if success {
        print("Success. Data1: \(data1). Data2: \(data2)")
    } else {
        print("Error. Data1: \(data1). Data2: \(data2)")
    }
}

I was wondering if you can use completion handlers as above without having to give it an argument to the parameter imgURL. So that I can call the downloadImageFromServer method like so: `downloadImageFromServer()` and that that function will return me the print statement? @Georgy @Sunshinejr — Caspert, Oct 27 '16 at 14:06

Return value after Alamofire dowloaded data

1 Answers1