Btukfyl

I am attempting to take a string from JSON data and set it to a variable. My problem is that the variable shows as empty. I am using JSONDecoder to retrieve the JSON data and setting the string to a variable outside of the function. I then want to use that variable inside of another function

When I print the variable it still shows up as blank even after the function has loaded. Within the function the string appears correctly.

Code:

var filmTitle = ""



override func viewDidLoad() {

    super.viewDidLoad()





loadFilms()

print(self.filmTitle) //Prints as an empty string



}



func loadFilms() {



    let id = filmId

    let apiKey = "97a0d64910120cbeae9df9cb675ad235"

    let url = URL(string: "https://api.themoviedb.org/3/movie/(id)?api_key=(apiKey)&language=en-US")

    let request = URLRequest(

        url: url! as URL,

        cachePolicy: URLRequest.CachePolicy.reloadIgnoringLocalCacheData,

        timeoutInterval: 10 )



    let session = URLSession (

        configuration: URLSessionConfiguration.default,

        delegate: nil,

        delegateQueue: OperationQueue.main

    )



    let task = session.dataTask(with: request, completionHandler: { (dataOrNil, response, error) in

        if let data = dataOrNil {

            do { let details = try! JSONDecoder().decode(Details.self, from: data)

        self.filmTitle = details.title

        print(self.filmTitle) //string prints correctly



                        }

                    }

                })





    task.resume()



}

What am I missing to correctly set the string to the variable?

Loading data from the internet is an asynchronous method. The print statement is being called before loadFilms() has completed.

Use a callback to get the data after it has completed.

func loadFilms(completion: @escaping (Details?, Error?) -> Void) { 

    //...



 let task = session.dataTask(with: request, completionHandler: { (dataOrNil, response, error) in

    if let data = dataOrNil {

        do { let details = try JSONDecoder().decode(Details.self, from: data)

     completion(details, nil) 





           } catch { 

               completion(nil, error) 

                }

            })



}

At the call site:

override func viewDidLoad() { 



   loadFilms { details, error in 



     if error { //* Handle Error */ } 



     self.filmTitle = details.title

     print(filmTitle)



    }



}

Web request are asynchronous and from the CP's perspective, take a long time to complete. When you call this:

override func viewDidLoad() {

    super.viewDidLoad()



    loadFilms()

    print(self.filmTitle) // loadFilms() hasn't finished so `filmTitle` is empty

}

It's better to set a property observer on filmTitle:

var filmTitle: String? = nil {

    didSet {

        print(filmTitle)



        Dispatch.main.async {

            // update your GUI

        }

    }

}

The solution to this problem was to reload the collection view that the array was being sent to within the decoder function after the data was set to the array.