iOS 14 & XCode 12 beta 2 - 从 Firebase 读取数据

Question

I'm coding an iOS app with XCode 12 beta 2, and I'm stuck because I need to read some data from Firebase. I took the code by default from Firebase documentation and added some stuff:

Auth.auth().signIn(withEmail: email, password: password) { (result, error) in
        
    print("Logged in!")
    
    // Loading Database
    var ref: DatabaseReference!
    ref = Database.database().reference()
        
    let userID = Auth.auth().currentUser?.uid
        
    ref.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
            
        // Get user values
        let value = snapshot.value as? NSDictionary
        let dataFirstname = value?["firstname"] as? String ?? ""
        let dataLastname = value?["lastname"] as? String ?? ""
            
        // Setup labels
        self.namesLabel.text = "\(dataFirstname) \(dataLastname)"
        self.passwordLabel.text = self.password
        self.emailLabel.text = self.email
            
      }) { (error) in
        print(error.localizedDescription)
    }
}

The problem is that "dataFirstname" and "dataLastname" aren't get from the database. The problem seems to come from the line "let value =....." from what I saw when debugging the code. I'm still new at Swift so, any help would be appreciated, Thanks for reading. and I hope you'll help me! -- Max.

Answer 1

You are getting nil if snapshot.value is not representable as an NSDictionary (which is kind of deprecated in Swift).

The quickest way to see the correct type is to log the object: print(snapshot.value)

You can also add a breakpoint and inspect the content

Answer 2

I changed my code but I still need help in a different way Here is what I've done:

// Loggin-in
Auth.auth().signIn(withEmail: email, password: password) { (result, error) in
        
    if error != nil {
            
        // Couldn't log-in
        self.alertUser("Error", error!.localizedDescription)
            
    } else {
            
        print("Logged in!")
        
        // Loading Database
        let userID = Auth.auth().currentUser?.uid
        let db = Firestore.firestore()
        let ref = db.collection("users").document(userID!)

        ref.getDocument { (document, error) in
            if let document = document, document.exists {
                    
                let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
                print("Document data: \(dataDescription)")
                    
                self.FirstName = dataDescription["firstname"]
                self.LastName = dataDescription["lastname"]
                    
                // Setup labels
                self.namesLabel.text = "\(self.FirstName) \(self.LastName)"
                self.passwordLabel.text = self.password
                self.emailLabel.text = self.email
                    
            } else {
                    
                print("Document does not exist")
            }
        }
    }
}

So the problem is that "dataDescription" is a collection with this format: ["lastname": Reikeb, "firstname": Max, "uid": dnefehuzihfz] and I don't know how to take stuff from this collection to put them in separated variables. I already tried with this:

self.FirstName = dataDescription["firstname"]
self.LastName = dataDescription["lastname"]

but it doesn't work

Answer 3

So I've succeeded to correctly read the data. For those who are interrested in it, here's my final code. Thanks to all the people who helped me!

// Loggin-in
Auth.auth().signIn(withEmail: email, password: password) { (result, error) in
        
    if error != nil {
            
        // Couldn't log-in
        self.alertUser("Error", error!.localizedDescription)
            
    } else {
            
        print("Logged in!")
        
        // Loading Database
        let userID = Auth.auth().currentUser?.uid
        let db = Firestore.firestore()
        let ref = db.collection("users").document(userID!)

        ref.getDocument { (document, error) in
            if let document = document, document.exists {
                    
                var dataDescription = document.data()
                print("Document data: \(dataDescription)")
                    
                // Get values from data
                self.FirstName = dataDescription?.removeValue(forKey: "firstname") as! String
                self.LastName = dataDescription?.removeValue(forKey: "lastname") as! String
                    
                // Setup labels
                self.namesLabel.text = "\(self.FirstName) \(self.LastName)"
                self.passwordLabel.text = self.password
                self.emailLabel.text = self.email
                    
            } else {
                    
                print("Document does not exist")
            }
        }
    }
}