为什么我的完成块不起作用？

Question

Implementing solution given here How to make a synchronous request using Alamofire?

I don't get any errors, it just doesn't work as expected. In tableViewController

override func viewDidLoad() {
    super.viewDidLoad()

    loadData() { (didCompleteRequest) in
        if (didCompleteRequest) {
            self.TodosTableView.delegate = self
            self.TodosTableView.dataSource = self
            print("loading successfull")
        } else {
            print("loading failed")
        }
    }
    print("leaving viewDidLoad")
}

func loadData(completion: @escaping (Bool) -> Void) {
    Alamofire.request(TodosViewController.serverAdress + "projects/index.json").responseJSON { response in
        do {
            // async stuff
        } catch {
            completion(false)
        }
        print("leaving loadData")
        completion(true)
    }
}

output I get

leaving viewDidLoad

leaving loadData

loading successfull

apparently, the first element should be the last one

Answer 1

First viewDidLoad is running in the main thread. So when you put this loadData() in viewDidLoad controls dispatched to background thread where alamofire works on, and the main thread continues and prints leaving viewDidLoad

Try this

 override func viewDidLoad() {
super.viewDidLoad()

  self.TodosTableView.delegate = self
  self.TodosTableView.dataSource = self

loadData() { (didCompleteRequest) in
    if (didCompleteRequest) {           
        self.TodosTableView.reloadData()
        print("loading successfull")
    } else {
        print("loading failed")
    }
}
print("leaving viewDidLoad")
}

Answer 2

You are call block code after get response from server. so first call "print("leaving viewDidLoad")".

response code get with delay so call block code with delay