We send APDU command to ISO-7816 tag and receive the resposne, but some error occurred.
Exceeding 1694 bytes will failure
We send the APDU command. The phone successfully get response from PN7150 when the length of response is under 1694 bytes, but we get an error when the length of response is greater than or equal to 1694 bytes.
The exception as follows : Error Domain=NFCError Code=100 "Tag connection lost"
Android can work
We use Android to test same function, it can be executed successfully.
I think the APDU command on iOS has the response limit or other issue.
It is the result of ours test on iOS :
- send 100 bytes, response 1529 bytes : occasionally success.
- send 100 bytes, response 1200 bytes : success.
- send 0 byte, response 1694 bytes : error.
- send 0 byte, response 1693 bytes : success.
Code
The following is the part of the send and receive APDU.
func tagReaderSession(_ session: NFCTagReaderSession, didDetect tags: [NFCTag]) {
var tag: NFCTag? = nil
for nfcTag in tags {
if case .iso7816(_) = nfcTag {
session.alertMessage = "Detect an iso7816 tag."
tag = nfcTag
}
}
if tag == nil {
session.invalidate(errorMessage: "No valid tag found.")
return
}
session.connect(to: tag!) { (error: Error?) in
if error != nil {
session.invalidate(errorMessage: "Connection error. Please try again.")
return
}
guard case let .iso7816(iso7816Tag) = tag else {
return
}
let CLA: UInt8 = 0x00
let INS: UInt8 = 0xB0
let p1: UInt8 = 0x00
let p2:UInt8 = 0x04
let data : Data = self.stringToHex(self.message) // sent data
let Le:Int = 1500 // extends APDU
let apduCommand = NFCISO7816APDU(instructionClass: CLA,instructionCode: INS,p1Parameter: p1,p2Parameter: p2,data: data,expectedResponseLength: Le)
iso7816Tag.sendCommand(apdu: apduCommand) { (response: Data, sw1:UInt8, sw2:UInt8, error: Error?) in
// if response > 1694 bytes , error occurred
if error != nil {
self.readerSession?.invalidate(errorMessage: "Send command tag error. Please try again.")
return
}
print(String(data:response,encoding: .ascii)!)
self.readerSession?.alertMessage = "Send Command Success!"
self.readerSession?.invalidate()
}
}
}Thank you.
