從函數返回數據（Swift）

Question

我試圖返回結果，並能夠從此函數訪問結果數組。 一切都在函數中工作，但是我無法從閉包外部返回任何內容或訪問結果或在函數內創建的任何變量。 我想從閉包外部訪問result.valueForKey（“id”）。 我怎樣才能做到這一點？

class ViewController: UIViewController, FBSDKLoginButtonDelegate {

var facebookid: NSString = ""
var username: NSString = ""
var userEmail:NSString = ""

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    if (FBSDKAccessToken.currentAccessToken() == nil)
    {
        let loginView : FBSDKLoginButton = FBSDKLoginButton()
        self.view.addSubview(loginView)
        loginView.center = self.view.center
        loginView.readPermissions = ["public_profile"]
        loginView.delegate = self

    } else {

        returnUserData()

        println(facebookid)  // This doesn't work

    }
}



    func returnUserData()
{

    let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: nil)
    graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in

        if ((error) != nil)
        {
            // Process error
            println("Error: \(error)")
        }
        else
        {

            self.facebookid = result.valueForKey("id") as NSString!
            self.username = result.valueForKey("name") as NSString!
            self.userEmail = result.valueForKey("email") as NSString!
            println(result) // This works


        }
    })
}

編輯：我確實根據下面的2個答案更改了代碼但仍然無法在viewDidLoad閉包上獲得任何數據返回。 * println（facebookid）不返回ViewDidLoad中的任何內容，而它在函數中的閉包內部。

Answer 1

您正在閉包內創建變量，這意味着它們只能在內部訪問。

您需要在類頂部的函數外部創建變量。

例如

 class YourClassName {

      var facebookid
      var username
      var userEmail


 func returnUserData()
 {
     let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath:  "me", parameters: nil)
     graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in

    if ((error) != nil)
    {
        // Process error
        println("Error: \(error)")
    }
    else
    {
        self.facebookid = result.valueForKey("id") as? String
        self.userName = result.valueForKey("name") as? String
        self.userEmail = result.valueForKey("email") as? String

    }
  })
 }
}

Answer 2

func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {       
        if error != nil {
            print(error.localizedDescription)
            return
        }


                print("user loged in with facebook")
                if((FBSDKAccessToken.current()) != nil) {
                    FBSDKGraphRequest(graphPath: "me", parameters: ["fields": "id, name, first_name, last_name, email, age_range, link, gender, locale, timezone, updated_time, verified"]).start(completionHandler: { (connection, result, error) -> Void in
                        if (error == nil){
                            print(result!)
                            print("Token: \((FBSDKAccessToken.current().tokenString)!)")
                            print("Token Expiration Date: \((FBSDKAccessToken.current().expirationDate)!)")
                        }
                    })
                }

    }