Create an object from firebase database - swift

Question

I'm using firebase to store user records. When a user logs in, I am trying to pull the record and create a user object to pass around amongst the view controllers as opposed to hitting the database multiple times.
class User: NSObject {
var name: String?
var email: String?
}
I have a variable, myUser: User? in my controller and would like to assign the record retrieved from firebase to that variable.
func retrieveUserWith(uid: String) {
Database.database().reference().child("users").child(uid).observe(.value, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: Any] {
let user = User()
user.name = dictionary["name"] as? String
user.email = dictionary["email"] as? String
self.myUser = user
}
})
}
Now I understand that the firebase call is asynchronous and I can't directly assign the created user to myUser variable as shown above.
Is there another way to assign user to myUser to avoid hitting the database every time I switch view controllers?

Answer 1

This is not really the correct way to get the info you want. Firebase already offers a sharedInstance of the User.
if let user = Auth.auth().currentUser {
let name = user.displayName // should check that this exists
let email = user.email // should check that this exists
}
Nonetheless, to achieve this the way you are looking to do so:
class User: NSObject {
var name: String
var email: String?
static var sharedInstance: User!
init(name: String, email: String) {
self.name = name
self.email = email
}
}
Calls to firebase are asynchronous, so you should have a completionHandler that will get called when the call is finished:
func retrieveUserWith(uid: String, completionHandler: #escaping () -> ()) {
Database.database().reference().child("users").child(uid).observe(.value, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: Any] {
let name = dictionary["name"] as? String ?? ""
let email = dictionary["email"] as? String ?? ""
let user: User = User(name: name, email: email)
User.sharedInstance = user
completionHandler()
}
})
}
Then to use the sharedInstance of the user elsewhere in your app you can do the following:
if let user = User.sharedInstance {
// do stuff here
}