ios - Swift 1.2 解析保存在后台错误

Question

我最近切换到 Swift 1.2 并注意到它破坏了我的少量 Parse 功能。我仍在努力思考为什么版本更新会破坏这些原本可以工作的方法，以及我应该如何解决它们。我看到的两个错误都在同一个 .saveInBackgroundWithBlock 函数中。

第一个错误出现在我的 .saveInBackgroundWithBlock 行:

函数签名“(Bool, NSError!) -> Void”与预期类型“@objc_block (Bool, NSError!) -> Void”不兼容

第二个位于出现注册错误时发生的 else 语句中，NSString { error = errorString }

“NSString”不能隐式转换为“String”；您是要使用“as”来显式转换吗？

完整代码如下:

import UIKit

class UserRegistrationViewController: UIViewController {


    func displayAlert(title:String, error:String) {

        var alert = UIAlertController(title: title, message: error, preferredStyle: UIAlertControllerStyle.Alert)

        alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: {
            action in



        }))

        self.presentViewController(alert, animated: true, completion: nil)


    }

    @IBOutlet var usernameTextField: UITextField!

    @IBOutlet var emailTextField: UITextField!

    @IBOutlet var passwordTextField: UITextField!


    override func viewDidLoad() {
        super.viewDidLoad()


    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    @IBAction func registerUser(sender: AnyObject) {

        var error = ""

        if usernameTextField.text == nil || emailTextField.text == nil || passwordTextField.text == nil {

            error = "Please enter a username, email and password"

        }


        if error != "" {

            displayAlert("Error In Form", error: error)

        } else {

            var user = PFUser.currentUser()

            user.username = usernameTextField.text
            user.password = passwordTextField.text
            user.email = emailTextField.text

            user.saveInBackgroundWithBlock {
                (succeeded: Bool!, signupError: NSError!) -> Void in
                if signupError == nil {

                    println(user.username)
                    println(user.password)
                    println(user.email)


                    self.performSegueWithIdentifier("successfulRegistration", sender: self)

                    /*self.navigationController?.setNavigationBarHidden(self.navigationController?.navigationBarHidden == false, animated: true)*/

                } else {

                    if let errorString = signupError.userInfo?["error"] as? NSString {
                        error = errorString
                    } else {

                        error = "Please try again later."

                    }


                    self.displayAlert("Could Not Sign Up", error: error)

                }
            }


        }


    }

Answer 1

首先，NSError 需要是一个可选的，而不是隐式解包

例如:

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