Sorani is the most widely spoken Kurdish dialect in both Iraq and Iran. There are many resources available both online and in print. Sorani is written in an a modified Arabic alphabet.
If people say they are from Suleymani, Erbil (Hewler), Kirkuk then Sorani is probably there first language. Many people who have Hawrami and Kelhuri as their mother tongue will also be fluent in Sorani.
Many Sorani speakers from Iran will not be very literate in Sorani. They might be pleased to have something printed in Sorani but would be able to read Farsi more easily.