Calling setValuesForKeys fails in my Swift 4 code

Question

I'm having this problem, im trying to retrieve data from the firebase database, but it's saying the profilepic isn't a key, but it is. This is the object class.

class User: NSObject {
    var firstname: String?
    var lastname: String?
    var username: String?
    var profilepic: String?
}

and this is me trying to retrieve

func getusers(){
        ref.child("Friends").child(currentuser!).observe(.childAdded, with: { (snapshot) in
            print(snapshot)
            if let dic = snapshot.value as? [String: AnyObject]{
                let user = User()
                user.setValuesForKeys(dic)
                print(user.firstname, user.lastname)

                DispatchQueue.main.async {
                    self.tableview.reloadData()
                }}
        }) { (error) in
            print(error.localizedDescription)
        }

    }

and the crash is here user.setValuesForKeys(dic).

Anyone has any idea why isn't working?

If you inspect `dic` before `setValuesForKeys`, what does the dictionary look like? — GetSwifty, Nov 16 '17 at 22:36
I think I found the problem, but idk how to solve it. It's crashing, because my User is returning nil, so it's returning nothing, i have to make snapshot throw the values into User class then retrieve to the dictionary with the actual values. — Gabriel Tavares, Nov 16 '17 at 22:39
the snapshot is working, is retrieving all the users, but my thing isn't throwing the retrieve values to my User class for some reason — Gabriel Tavares, Nov 16 '17 at 22:40
Don't force unwrap values, that should fix 95% of mistakes you are doing. — Dominik Bucher, Nov 16 '17 at 23:11
can you please show the Dict output you getting from server as I think something is wrong with the method you had written to get data in user keys — iOS Geek, Nov 17 '17 at 05:05

Paulo Mattos · Answer 1 · 2017-11-17T02:02:33.063

Try this instead:

@objcMembers
class User: NSObject {
    ...
}

The setValuesForKeys API is implemented by the Foundation framework and requires Objective-C compatibility.

The rules for exposing Swift code to Objective-C have changed considerably in Swift 4. Please check the evolution proposal for further information.

User class design. If any of the four properties can be missing from Firebase than your class design might be a good fit. Otherwise, consider declaring the fixed properties as non-optional and creating an initializer instead.

score 1 · Answer 2 · answered Nov 17 '17 at 02:11

Change your User declaration to this:

class User: NSObject {
    @objc var firstname: String?
    @objc var lastname: String?
    @objc var username: String?
    @objc var profilepic: String?
}

In Swift 4, Objective-C cannot see your instance properties unless you expose them explicitly.

Calling setValuesForKeys fails in my Swift 4 code

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