ios - 如何在 Xcode 8、swift 3 中将 Facebook 值发送到下一个屏幕

Question

我正在整理一系列注册页面，首先向用户显示一个“使用 Facebook 创建帐户”按钮，用于登录，然后向他们显示一个充满空文本框的基本注册页面。但是，我尝试使用从图形请求收集的用户值填充其中一些文本框。

这是带有注册按钮的第一个屏幕:

import UIKit
import FBSDKLoginKit

class RegisterVC: UIViewController, FBSDKLoginButtonDelegate {
var fbLoginSuccess = false

var fbName:String!
var fbEmail:String!

override func viewDidLoad() {
    super.viewDidLoad()

    let loginButton = FBSDKLoginButton()
    view.addSubview(loginButton)
    loginButton.frame = CGRect(x: 82, y: 325, width: view.frame.width - 210, height: 59)

    loginButton.delegate = self
}

func loginButtonDidLogOut(_ loginButton: FBSDKLoginButton!) {
    print("Did log out of facebook")
}

func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {
    if error != nil {
        print(error)
        return
    }
    print("Successfully logged in")

    FBSDKGraphRequest(graphPath: "/me", parameters: ["fields": "id, name, email"]).start {(connection, result, err) in
        if err != nil {
            print("Failed to start graph request", err)
            return
        } else {

            guard let data = result as? [String:Any] else {return}

            let fbEmail = data["email"]
            let fbName  = data["name"]

            func prepare(for segue: UIStoryboardSegue, sender: Any?) {
            let vc = segue.destination as? CreateAccountVC
            vc!.email.text = self.fbEmail
            vc!.fullname.text = self.fbName
                }

        }

        print(result)
    }

    performSegue(withIdentifier: "regSegue", sender: RegisterVC.self)
}

这些是下一个屏幕上的文本框:

import UIKit

class CreateAccountVC: UIViewController {
    @IBOutlet weak var fullname: UITextField!
    @IBOutlet weak var username: UITextField!
    @IBOutlet weak var age: UITextField!
    @IBOutlet weak var email: UITextField!
    @IBOutlet weak var verifyEmail: UITextField!
    @IBOutlet weak var password: UITextField!
    @IBOutlet weak var verifyPassword: UITextField!

上面的所有代码都向我展示了注册页面，但文本框是空的并且没有填充 Facebook 数据。我不是一个出色的编码员，但帮助确实很有用。如果您有任何解决方案，请告诉我!谢谢。

Answer 1

此代码片段中存在问题:

func prepare(for segue: UIStoryboardSegue, sender: Any?) {
            let vc = segue.destination as? CreateAccountVC
            vc!.email.text = self.fbEmail
            vc!.fullname.text = self.fbName

当此处更新其 .text 属性时，CreateAccountVC 的文本字段尚未创建，此时文本字段为 nil .
评估将从 Graph API 检索的 String 对象直接传递给 CreateAccountVC，然后使用它们更新文本字段。

考虑将现有的实现改为以下几行:

class CreateAccountVC: UIViewController {
    var fbName:String!
    var fbEmail:String!
    @IBOutlet weak var fullname: UITextField!
    @IBOutlet weak var username: UITextField!
    @IBOutlet weak var age: UITextField!
    ...

上面提到的代码片段将更改为:

func prepare(for segue: UIStoryboardSegue, sender: Any?) {
                let vc = segue.destination as? CreateAccountVC
                vc!.fbName = self.fbName
                vc!.fbEmail = self.fbEmail
                ...