How can I convert an array to string in swift?

I want to convert an array to string like this

let myArray:[Any] = ["element 1", "element 2", ["element 3.1", "element 3.2"], "element 4"]

to

let convertedString = "[\"element 1\",\"element 2\",\"[\\\"element 3.1\\\",\\\"element 3.2\\\"]\",\"element 4\"]"

I have tried this

do {
    let jsonData: Data = try JSONSerialization.data(withJSONObject: myArray, options: [])
    if  let jsonString = NSString(data: jsonData, encoding: String.Encoding.utf8.rawValue) {
        print(jsonString)
    }

} catch let error as NSError {
    print("Array convertIntoJSON - \(error.description)")
}

However I get this result

["element 1","element 2",["element 3.1","element 3.2"],"element 4"]

I have done this in java by using JSONArray. I just call toString method to do this in java. I need to get third element as a string like given example above.