Posts a web form data to the server.
public func postWebForm(url: String, fields: String, fileField: String, fileName: String, contentType: String) throws -> Void
This variant of the POST method provides means to submit a form (as in a web browser) with an optional file attachment. Fields are expected to contain a list of field names and values in "Name=Value" format separated with EOLs. This list can be empty.
If including a file with your request, use the FileField and FileName properties to specify the file field name and the local filename for the uploaded file. Use ContentType to override the default content type chosen by the client, e.g., "application/x-www-form-urlencoded".
Note that any parameters you intend to pass to this method should be properly encoded before this method is called.