There are four different types of codes. They all start with a letter to signify what type of code it is.

Pay to a swish number.

A <swish number>

A0708123456

Pay a specified amount to a swish number.

B <swish number> ; <amount>

B0708123456;100

Pay a specified amount to a swish number, with a custom message and specify what fields are editable.

C <swish number> ; <amount> ; <message> ; <editable fields>

<message> and <editable fields> can be of length 0, but the semicolons inbetween are required.

This can be used to prefill a value in the fields but keep the fields editable by the user.

Swish expects an integer value (in base 10), and the editable fields are represented by a bitstring.

PHONE_EDITABLE   = 0b001
AMOUNT_EDITABLE  = 0b010
MESSAGE_EDITABLE = 0b100

To make both the phone number and amount field editable just bitwise OR the two values.

PHONE_EDITABLE | AMOUNT_EDITABLE  // = 0b011
                                  // converted to base 10 = 3

Functionally same as the B example:

C0708123456;100;;

Message will be put in the message field:

C0708123456;100;Message;

Message will be put in the message field:

C0708123456;100;Message;

Message will be put in the message field, phone number and amount is editable (but message is not):

C0708123456;100;Message;3

To be documented… Seems to be a base64-string.