Cannot assign to value: function call returns immutable value ([[String:AnyObject]])

Question

why am i getting this error at the line " let postObject = [String:AnyObject] = [ "

Cannot assign to value: function call returns immutable value

    @IBAction func HandleSendButton(_ sender: Any) {
    let postRef = Storage.storage().reference().child("messages").child("\(selectedUser).[“id”]")

    let postObject = [[String:AnyObject]]() = [
        "From": [
            "uid": User.uid,
            "username": User.username,
            "photoURL": User.photoURL.absoluteString
        ],
        "Message": textView.text,
        "timestamp": [".sv":"timestamp"]
        ] as [String:Any]

    postRef.setValue(postObject, withCompletionBlock: { error, ref in
        if error == nil {
            self.dismiss(animated: true, completion: nil)
        } else {
            // Handle the error
        }
    })
}

Answer 1

Just remove the = [[String:AnyObject]]() part:

let postObject = [

or

let postObject: [String: Any] = [

Answer 2

It's supposed to be like this:

let postObject: [[String: Any]] = [[
    "From": [
        "uid" : User.uid,
        "username" : User.username,
        "photoURL" : User.photoURL.absoluteString
    ],
    "Message" : textView.text,
    "timestamp" : [".sv" : "timestamp"]
    ]]

let postObject part declares a constant, : [[String:AnyObject]] declares its type (notice that not using = ), and finally after = is the literal object that initializes it.

Answer 3

There are a few issues to be addressed.

Let's assume your Firebase looks like this

root
  questions
    uid_0
      From:
        photoUrl: "some photoUrl"
        uid: "some userid"
        username: "some username" 
      message: "some message"
      timestamp: "some timestamp"

If you want to create a new questions node this will create it in that structure

let uid = Auth.auth().currentUser?.uid
let postRef = self.ref.child("questions").child(uid!) //self.ref is a class var*

let dict: [String: Any] = ["From":
    ["uid": "some uid",
     "username": "some username",
     "photoUrl": "some url"],
    "message": "some message",
    "timestamp": "some timestamp"
]

postRef.setValue(dict, withCompletionBlock: { error, ref in
    if error == nil {
        self.dismiss(animated: true, completion: nil)
    } else {
        // Handle the error
    }
})

With this, we get the uid and define the reference to where the data is written.

Then the simple use of a dictionary; Firebase uses key: value pairs to store it's data and we define a dictionary to contain a key, which is a String and the values can be a kind of Any.

let dict: [String: Any]

That allows the first element to be a String: Dictionary, and the second and third elements to be String: String.

*self.ref points to my root Firebase node. Edit to point to yours.

Answer 4

Try this:

    let postObject: [String: Any] = [
    "From": [
        "uid": User.uid,
        "username": User.username,
        "photoURL": User.photoURL.absoluteString
        ] as [String: Any],
    "Message": textView.text,
    "timestamp": [".sv":"timestamp"]
    ] as [String: Any]

The necessary changes are:

• remove the initial "=" and "()"
• replace "[String: AnyObject]" with "[String: Any]"
• cast the "From" dictionary value to "as [String: Any]"

Let me know if this works for you.