(Well, I've googled it but couldn't find anything useful. All the sources I've found were obsolete. iOS and Facebook are continuously changing over time.)
I'd like to sync the birthdays of my friends on Facebook with my calendar on my iPhone 6 with iOS 9.1. The reason why I want to do that is I don't want to check Facebook everyday to see if there is a birthday on that day. I use the calendar on my iPhone several times a day and it would be very handy to have Facebook birthdays on my calendar.
How can I achieve this?