ios – The right way to look ahead to an API request to complete earlier than storing knowledge from operate callback?

In a private venture of mine, I’ve created an API caller to retrieve a person’s saved tracks from the Spotify API. The Spotify endpoint which I’m utilizing has a restrict (most of fifty tracks per request) in addition to an offset (beginning index of first observe in request), which is why I made a decision to make use of a FOR loop to get a collection of observe pages (every 50 tracks) and append them to a worldwide array. The information is loaded from the primary thread, and whereas the information is being requested, I show a toddler view controller with a spinner view. As soon as the information request has accomplished, I take away the spinner view, and transition to a different view controller (passing the information as a property).

I’ve tried many issues, however the array of tracks is all the time empty following the API request. I’ve a sense it has to do with the synchronicity of my request, or possibly its potential that I am not dealing with it appropriately. Ideally, I wish to wait till the request from my API finishes, then append the consequence to the array. Do you could have any options on how I might clear up this? Any assist is way appreciated!

func createSpinnerView() {

    let loadViewController = LoadViewController.instantiateFromAppStoryboard(appStoryboard: .OrganizeScreen)
    add(asChildViewController: loadViewController)

    DispatchQueue.important.async { [weak self] in
        if (self?.dropdownButton.dropdownLabel.textual content == "My saved music") {
            self?.fetchSavedMusic() { tracksArray in
                self?.tracksArray = tracksArray
            }
        }
        ...
        self?.take away(asChildViewController: loadViewController)
        self?.navigateToFilterScreen(tracksArray: self!.tracksArray)
    }
}

non-public func fetchSavedMusic(completion: @escaping ([Tracks]) -> ()) {
    let restrict = 50
    var offset = 0
    var complete = 200
    for _ in stride(from: 0, to: complete, by: restrict) {
        getSavedTracks(restrict: restrict, offset: offset) { tracks in
            //complete = tracks.complete
            self.tracksArray.append(tracks)
        }
        print(offset, restrict)
        offset = offset + 50
    }
    completion(tracksArray)
}

non-public func getSavedTracks(restrict: Int, offset: Int, completion: @escaping (Tracks) -> ()) {
    APICaller.shared.getUsersSavedTracks(restrict: restrict, offset: offset) { (consequence) in
        change consequence {
        case .success(let mannequin):
            completion(mannequin)
            print("success")
        case .failure(let error):
            print("Error retrieving saved tracks: (error.localizedDescription)")
            print(error)
        }
    }
}

non-public func navigateToFilterScreen(tracksArray: [Tracks]) {
    let vc = FilterViewController.instantiateFromAppStoryboard(appStoryboard: .OrganizeScreen)
    vc.paginatedTracks = tracksArray
    present(vc, sender: self)
}