登录Facebook获取用户电子邮件ID swift 3时获取空值

在Swift 3中，要登录Facebook并获取用户的电子邮件地址，你需要使用Facebook SDK。以下是详细的步骤和代码示例，帮助你解决获取空值的问题。

步骤 1: 安装Facebook SDK

首先，确保你已经在项目中安装了Facebook SDK。你可以使用CocoaPods来安装：

pod 'FBSDKCoreKit'
pod 'FBSDKLoginKit'

然后在终端运行：

pod install

步骤 2: 配置Info.plist

在项目的Info.plist文件中添加以下内容：

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>fbYOUR_APP_ID</string>
        </array>
    </dict>
</array>
<key>FacebookAppID</key>
<string>YOUR_APP_ID</string>
<key>FacebookDisplayName</key>
<string>YOUR_APP_NAME</string>
<key>LSApplicationQueriesSchemes</key>
<array>
    <string>fbapi</string>
    <string>fb-messenger-share-api</string>
    <string>fbauth2</string>
    <string>fbshareextension</string>
</array>

确保将YOUR_APP_ID和YOUR_APP_NAME替换为你的Facebook应用的ID和名称。

步骤 3: 初始化Facebook SDK

在你的AppDelegate.swift文件中初始化Facebook SDK：

import FBSDKCoreKit

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    ApplicationDelegate.shared.application(application, didFinishLaunchingWithOptions: launchOptions)
    return true
}

func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
    return ApplicationDelegate.shared.application(app, open: url, options: options)
}

步骤 4: 实现登录和获取用户信息

在你的ViewController中实现登录和获取用户信息：

import UIKit
import FBSDKLoginKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func loginButtonTapped(_ sender: UIButton) {
        let loginManager = LoginManager()
        loginManager.logIn(permissions: ["public_profile", "email"], viewController: self) { loginResult in
            switch loginResult {
            case .success(let grantedPermissions, _, _):
                if grantedPermissions.contains("email") {
                    self.getUserProfile()
                }
            case .cancelled:
                print("User cancelled login.")
            case .failed(let error):
                print("Login failed with error: \(error.localizedDescription)")
            }
        }
    }

    func getUserProfile() {
        if let accessToken = AccessToken.current {
            GraphRequest(graphPath: "me", parameters: ["fields": "email"]).start { connection, result, error in
                if let error = error {
                    print("Failed to get user profile: \(error.localizedDescription)")
                    return
                }
                
                guard let userData = result as? [String: Any], let email = userData["email"] as? String else {
                    print("Email is nil")
                    return
                }
                
                print("User email: \(email)")
            }
        }
    }
}