无法为类型“ AnyObject？”调用初始化程序没有参数Swift 4.2

Question

var loggedInUser = AnyObject?() //Cannot invoke initializer for type 'AnyObject?' with no arguments

不知道为什么它会给我这个我不熟悉的错误

var databaseRef = Database.database().reference()
var storageRef = Storage.storage().reference()

// structure definition goes here
override func viewDidLoad() {
    super.viewDidLoad()

    self.loggedInUser = Auth.auth()?.currentUser
    self.databaseRef.child("user_profiles").child(self.loggedInUser!.uid).observeSingleEventOfType(.Value) { (snapshot:DataSnapshot) in

---

var databaseRef = Database.database().reference()
var storageRef = Storage.storage().reference()

// structure definition goes here
override func viewDidLoad() {
    super.viewDidLoad()

    self.loggedInUser = Auth.auth()?.currentUser

    self.databaseRef.child("user_profiles").child(self.loggedInUser!.uid).observeSingleEventOfType(.Value) { (snapshot:DataSnapshot) in

Answer 1

Firbase类型为User，因此将其声明为

var loggedInUser: User?

Answer 2

无法以您的方式初始化AnyObject。您可以声明为可选变量

以这种方式声明：

var loggedInUser : AnyObject?