ios - 在 View Controller 中从 App Delegate 访问变量

Question

我正在我的应用程序上实现 Google 登录，我需要访问用户 ID 和名字/姓氏。存储该数据的变量位于 App Delegate 中。我在互联网上来回搜索，寻找如何在 Swift 3 中执行此操作，但一无所获。

这是 App Delegate(至少是重要的部分):

class AppDelegate: UIResponder, UIApplicationDelegate, GIDSignInDelegate {

var window: UIWindow?
var databaseRef: FIRDatabaseReference!

var userID = String()
var givenName = String()
var familyName = String()

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.

    // Use Firebase library to configure APIs
    FIRApp.configure()

    GIDSignIn.sharedInstance().clientID = FIRApp.defaultApp()?.options.clientID
    GIDSignIn.sharedInstance().delegate = self

    return true
}

func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {

    return GIDSignIn.sharedInstance().handle(url,
                                             sourceApplication: options[UIApplicationOpenURLOptionsKey.sourceApplication] as? String,
                                             annotation: options[UIApplicationOpenURLOptionsKey.annotation])
}

func sign(_ signIn: GIDSignIn!, didSignInFor user: GIDGoogleUser!, withError error: Error!) {

    if let error = error {
        print(error.localizedDescription)
        return
    }
    print("User signed into Google")

    let authentication = user.authentication
    let credential = FIRGoogleAuthProvider.credential(withIDToken: (authentication?.idToken)!,
                                                      accessToken: (authentication?.accessToken)!)

    FIRAuth.auth()?.signIn(with: credential) { (user, error) in
        print("User Signed Into Firebase")


        self.databaseRef = FIRDatabase.database().reference()

        self.databaseRef.child("user_profiles").child(user!.uid).observeSingleEvent(of: .value, with: { (snapshot) in

            let snapshot = snapshot.value as? NSDictionary

            if(snapshot == nil)
            {
                self.databaseRef.child("user_profiles").child(user!.uid).child("name").setValue(user?.displayName)
                self.databaseRef.child("user_profiles").child(user!.uid).child("email").setValue(user?.email)
            }


        })

    }

    userID = user.userID
    givenName = user.profile.givenName
    familyName = user.profile.familyName


    continueToWallet()
}

在 View Controller 中，我正在调用 App delegate 并尝试接收数据，但它给我一个错误提示，“实例成员‘User ID’不能用于类型‘AppDelegate’”

class addToWalletController: UIViewController {

var ID = String()

let delegate = UIApplication.shared.delegate as! AppDelegate
let user = AppDelegate.userID
let firstName = AppDelegate.givenName
let lastName = AppDelegate.familyName

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

}

我还尝试在 =AppDelegate.userID 中将 AppDelegate 与委托(delegate)切换，但它给了我同样的错误。怎么回事？

Answer 1

错误消息告诉您属性初始值设定项在“self”可用之前运行。

也许你应该在 viewDidLoad 中初始化它

let delegate = UIApplication.shared.delegate as! AppDelegate
var user: String?
var firstName: String?
var lastName: String?

override func viewDidLoad() {
    super.viewDidLoad()

    user = delegate.userID
    firstName = delegate.givenName
    lastName = delegate.familyName
}