JSONSerialization Invalid type in JSON write (_SwiftValue)

Question

Why does the following code give me the error:

Invalid type in JSON write (_SwiftValue).

The error is thrown on this line:

Answer 1

Just in case anyone is still having problems and is using Enums, another cause may be if you are passing an Enum value and not it's rawValue.

Example:

enum Status: String {
  case open
  case closed
}

instead of passing the enum:

params = ["status": Status.open]

pass

params = ["status": Status.open.rawValue]