How to create JSON from a dictionary in Swift 4?

After trying out various ways the below way is what worked for me for getting the exact format required by the backend.

    var messageDictionary = [
        "sender":"[email protected]",
        "recipients":["[email protected]"],
        "data":[
            "text" : data
        ]
        ] as [String : Any]

        let jsonData = try! JSONSerialization.data(withJSONObject: messageDictionary)
        let jsonString = NSString(data: jsonData, encoding: String.Encoding.utf8.rawValue)