NSJSONSerialization.JSONObjectWithData changes field type

Question

I'm getting the following JSON response from the server:

{
   "userId":"123456789",
   "displayName":"display name"
}

When I use NSJSONSerialization.JSONObjectWithData and then prints the result NSDictionary I see in the console the following:

userId = 123456789 displayName = "display name"

Why do JSONObjectWithData changes the userId field type from String to a number?

Answer 1

It doesn't. The JSON deserialisation respects the data type and will maintain it. You can't tell the data type from a simple description log, you need to actually interrogate the class. The description log will quote some things if it makes more sense for the human reader, like spaces in the description, but it also omits quotes in some cases.