我得到一个错误
Value of type 'AppDelegate?' has no member 'present'
当我试图让我的用户保持登录状态时，即使应用已退出。
这是我的 View Controller ，知道如何让我的用户保持登录状态吗？为什么我会收到此错误？
我在我的代码中使用 Firebase 作为我的数据库。
登录 View Controller .swift
import UIKit
import Firebase
class LoginViewController: UIViewController, UITextFieldDelegate {
@IBOutlet weak var emailField: UITextField!
@IBOutlet weak var pwField: UITextField!
func createAlert(title:String, message:String) {
let alert=UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "error" , style: UIAlertActionStyle.default, handler: { (action) in alert.dismiss(animated: true, completion: nil)
}))
self.present(alert, animated:true, completion: nil)
}
/* @IBAction func emailKeyboardField(_ sender: Any) {
hideKeyboard()
}
func hideKeyboard() {
emailField.resignFirstResponder()
pwField.resignFirstResponder()
}
*/
override func viewDidLoad() {
super.viewDidLoad()
emailField.delegate = self
// Do any additional setup after loading the view.
}
func emailKeyField(_ emailField: UITextField) -> Bool {
self.view.endEditing(true)
return true
}
@IBAction func loginPressed(_ sender: Any) {
guard emailField.text != "", pwField.text != "" else {return}
FIRAuth.auth()?.signIn(withEmail: emailField.text!, password: pwField.text!, completion: { (user, error) in
if let error = error {
print(error.localizedDescription)
self.createAlert(title: "Error", message: "We could not locate your account. Check your email and password.")
}
if let user = user {
let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "usersVC")
self.present(vc, animated: true, completion: nil)
}
})
}
}
AppDelegate.swift
import UIKit
import Firebase
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
var window: UIWindow?
var actIdc = UIActivityIndicatorView(activityIndicatorStyle: .whiteLarge)
var container: UIView!
private let auth = FIRAuth.auth()
class func instance() -> AppDelegate {
return UIApplication.shared.delegate as! AppDelegate
}
func showActivityIndicator() {
if let window = window {
container = UIView()
container.frame = window.frame
container.center = window.center
container.backgroundColor = UIColor(white: 0, alpha: 0.8)
actIdc.frame = CGRect(x: 0, y: 0, width: 40, height: 40)
actIdc.hidesWhenStopped = true
actIdc.center = CGPoint(x: container.frame.size.width / 2, y: container.frame.size.height / 2)
container.addSubview(actIdc)
window.addSubview(container)
actIdc.startAnimating()
}
}
func dismissActivityIndicatos() {
if let _ = window {
container.removeFromSuperview()
}
}
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
auth?.addStateDidChangeListener { [weak self] (_, user) in
if let user = user {
let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "usersVC")
self.present(vc, animated: true, completion: nil) //error on this line
// user is already logged in
} else {
// user is not logged in
}
}
FIRApp.configure()
return true
}
func applicationWillResignActive(_ application: UIApplication) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
}
func applicationDidEnterBackground(_ application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(_ application: UIApplication) {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(_ application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
func applicationWillTerminate(_ application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
}
我们将不胜感激。
最佳答案
App delegate 不是 ViewController 类型，因此它没有显示 View 的 present 方法。相反，您可以做的是使用它的窗口显示 View :
let storyboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let homeC = storyboard.instantiateViewController(withIdentifier: "YOUR_VIEWCONTROLLER_IDENTIFIER_IN_STORYBOARD") as? HomeC
if homeC != nil {
homeC!.view.frame = (self.window!.frame)
self.window!.addSubview(homeC!.view)
self.window!.bringSubview(toFront: homeC!.view)
}
关于ios - 错误 : Value of type 'AppDelegate?' has no member 'present' ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45647870/