Q:

Updating the count of an object's keys by appending a string

WatchKit has a presenter method that presents a QuickReplyButton with predetermined text replies and those replies can be sent to a UI element such as a label in a cell/row. 
I have inserted the row into the last position however each subsequent call inserts the new reply above the previous reply not below.
I attempted to append the text selection choice to the end of the chat model's message array using self.chats.append(text as AnyObject), but the choice is a string and I am unable to append a string to the chat model array. Value of type 'String' does not conform to 'AnyObject'. If I completely omit self.chats.append(text as AnyObject) it works as shown.
ChatDetailController
// ...
// start of @IBAction
// ...

    self.chats.append(text as AnyObject) // how do I write this?
    let newIndex = self.chats.count - 1
    //...

    })

Model
public struct ChatModel: Codable {
    public var message: String
    // more properties

    enum CodingKeys: String, CodingKey {
        case message = "messageText"
        // more properties
    }

    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.message = try container.decode(String.self, forKey: .message)
        // more properties
    }

    public func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(self.message, forKey: .message)
        // more properties
    }

}

json
[
  {
    "fromId": "wx1234skjksmsjdfwe234",
    "toId": "wx43922sdkfjsfmmxdfmx",
    "messageText": "Have you hopped on the bus Gus?",
    "imageUrl": "https://i.imgur.com/PJcyle7.jpg",
    "read": "true"
  },

// more objects.

]

A:

I have update your ChatModel. Use this model struct. You can init from json decoder or from your run time values. 
public struct ChatModel: Codable {
public var message: String
public var fromId: String
public var toId: String
public var imageUrl: URL?

enum CodingKeys: String, CodingKey {
    case message = "messageText"
    case fromId = "fromId"
    case toId = "toId"
    case imageUrl = "imageUrl"
    //case read = "read"
}

init (message:String , fromId:String, toID : String, imgUrl : URL?) {
    self.message = message
    self.fromId = fromId
    self.toId = toID
    self.imageUrl = imgUrl
}

public init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    self.message = try container.decode(String.self, forKey: .message)
    self.fromId = try container.decode(String.self, forKey: .fromId)
    self.toId = try container.decode(String.self, forKey: .toId)
    self.imageUrl = try container.decode(URL.self, forKey: .imageUrl)
    //self.read = try container.decode(Bool.self, forKey: .read)
}

public func encode(to encoder: Encoder) throws {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(self.message, forKey: .message)
    try container.encode(self.fromId, forKey: .fromId)
    try container.encode(self.toId, forKey: .toId)
    try container.encode(self.imageUrl, forKey: .imageUrl)
    //try container.encode(self.read, forKey: .read)
}

}

And this is how you can create chatModel object to inset in chats array 
Note: Use same fromID and ToID you have received from json 
    let newChat = ChatModel(message: "test", fromId: "fromID", toID: "tOID", imgUrl: nil)
    self.chats.append(newChat)

Now insert row in table at end

