How to choose which sector to write to ? And store nice data to a variable ?

[wanegain3]

Hi there !

Congrats for this nice library. I have 2 questions. Sorry for that but I couldn't find an online reference/doc somewhere beyound github.

QUESTION 1 : about writing

I am triying to write stuff to a MIFARE CLASSIC card.

I tried to use either :
ndefMessage.addTextRecord("hello, world");
or
ndefMessage.addUriRecord("http://arduino.cc");

However I need to write new stuff to prewritten tags. I would like to do it on sector 3 for example, because sector 1 already contains data. Is there any (easy) way to do this ? So far it seems to be written on sector 1 ?

QUESTION 2 : about storing data

Also when I get the records, the data begins by either a . or a .en (or a square !)
I saw the example on github to print the data to serial and it looks fine, however I need to store it into a variable. I kinda manage to do it but it looks pretty ugly. Is there a nicer way to do it ?

for(int i=0;i<message.getRecordCount();i++)
{
NdefRecord record = message.getRecord(i);
int payloadLength = record.getPayloadLength();
byte payload[payloadLength];
record.getPayload(payload);
String data = (char *)payload;
data = data.substring(3,data.length()-2);
show(data); //my own method to print to serial. Could be serial here.
}

Thanks a lot !