How to update particular value of child in Firebase DB

Question

I am following this document. Following is my code for update:

func updateDealResultToServer(key:String,dealResult : String)
{

    let post = [\"dealResul\"         


        

Answer 1

let ref = FIRDatabase.database().reference().root.child("users").child("childKey").updateChildValues(["childKeyForUpdate": "NewData"])