ios - 如何消除下标错误的不明确使用？

Question

import UIKit
import Parse
import FBSDKCoreKit
import ParseFacebookUtilsV4

class SignUpViewController: UIViewController
{


    @IBOutlet weak var emailAddress: UILabel!
    @IBOutlet weak var ProfileName: UILabel!
    @IBOutlet weak var ProfilePic: UIImageView!
    override func viewDidLoad()
    {
        super.viewDidLoad()

        let requestParameters = ["fields": "id, email, first_name, last_name"]

        let userDetails = FBSDKGraphRequest(graphPath: "me", parameters: requestParameters)

        userDetails.startWithCompletionHandler { (connection, result, error:NSError!) -> Void in

            if(error != nil)
            {
                print("\(error.localizedDescription)")
                return
            }

            if(result != nil)
            {
      // The next Four lines show the same error as ambiguous Use of Subscript
                let userId:String = result["id"] as! String 
                let userFirstName:String? = result["first_name"] as? String
                let userLastName:String? = result["last_name"] as? String
                let userEmail:String? = result["email"] as? String


                self.ProfileName.text = userFirstName! + " " + userLastName!

                let myUser:PFUser = PFUser.currentUser()!

                // Save first name
                if(userFirstName != nil)
                {
                    myUser.setObject(userFirstName!, forKey: "first_name")

                }

                //Save last name
                if(userLastName != nil)
                {
                    myUser.setObject(userLastName!, forKey: "last_name")
                }

                // Save email address
                if(userEmail != nil)
                {
                    myUser.setObject(userEmail!, forKey: "email")
                     self.emailAddress.text = userEmail
                }

                dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {

                    // Get Facebook profile picture
                    let userProfile = "https://graph.facebook.com/" + userId + "/picture?type=large"

                    let profilePictureUrl = NSURL(string: userProfile)

                    let profilePictureData = NSData(contentsOfURL: profilePictureUrl!)

                    if(profilePictureData != nil)
                    {
                        let profileFileObject = PFFile(data:profilePictureData!)
                        myUser.setObject(profileFileObject!, forKey: "profile_picture")
                        let image=UIImage(data: profilePictureData!)
                        self.ProfilePic.image=image

                    }


                    myUser.saveInBackgroundWithBlock({ (success:Bool, error:NSError?) -> Void in

                        if(success)
                        {
                            print("User details are now updated")
                        }

                    })

                }

            }

        }
    }

    override func didReceiveMemoryWarning()
    {
        super.didReceiveMemoryWarning()

    }

}

代码之前运行过，但在 Xcode 更新后显示此错误。

Answer 1

而不是使用

if(result != nil)

你应该这样做

if let result = result 

并使用分支内展开的值。

这样，如果有必要，你也可以沮丧，例如:

if let result = result as? NSDictionary

如果你需要告诉编译器result是一个NSDictionary。

此消息中的 ambiguously 意味着编译器无法推断 result 的类型(在 Swift 2.2 中，编译器对类型更加严格，并且不会推断出结果的类型)。不喜欢“猜测”)。