功能无法按所需顺序执行

Question

我正在创建一个应用程序，我必须首先检查登录状态，然后必须决定要呈现哪个ViewController。而且因为我必须使用大量的URL才能在整个项目中获得并获得价值，所以我制作了一个单独的文件。该文件获取URL并返回我需要的Dictionary。

我在viewDidLoad调用该方法，并使用名为handleData的其他函数中的值。但每次handleData在单独的类中的函数之前执行。有没有解决方案，以便我可以按所需的顺序执行功能？

以下是摘录：

class LoadingViewController: UIViewController {

    @IBOutlet var activity: UIActivityIndicatorView!
    let fetchData = FetchingData()
    var ifHasAccount: NSDictionary!

    var acStatus: String?


    override func viewDidLoad() {
        super.viewDidLoad()
        handleData()
        ifHasAccount = NSDictionary()
        activity.startAnimating()
    }
    func handleData(){

        fetchData.urlForHit = "Some URL"
        ifHasAccount = fetchData.fetchData()
        print(ifHasAccount)
    }
}

和其他类，即

  

FetchingData（）

它是：

class FetchingData{


    private var _urlForHit: String?
    var _aDictionary: NSDictionary?

    var urlForHit: String{
        get{
            return _urlForHit!
        }
        set{
            _urlForHit = newValue
        }
    }

    func fetchData() -> NSDictionary {
        var aDictionary = NSDictionary()
        let urlToHit = URL(string: _urlForHit!)
        var request = URLRequest(url: urlToHit!)
        request.setValue(UserDefaults.standard.value(forKey: "DEVICEID")! as? String, forHTTPHeaderField: "deviceId")
        request.setValue(UserDefaults.standard.value(forKey: "FCMID")! as? String, forHTTPHeaderField: "fcmId")
        request.setValue("iOS", forHTTPHeaderField: "deviceType")
        let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
            if error != nil{
                print((error?.localizedDescription)!)
                return
            }
            guard let response = response as? HTTPURLResponse, 200..<300 ~= response.statusCode else {print("Response out of range"); return}
            if data != nil{
                do{
                    aDictionary = try! JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as! NSDictionary
                    print(aDictionary)
                }
            }
            else
            {
                print("Data nil")
            }
        }
        task.resume()

        self._aDictionary = aDictionary
        return _aDictionary!
    }
}