Label always two digits

Hey I'm making a timer app that has both minutes and seconds. To do this I am using two different labels. How can I make sure it is always two digits (10:01 not 10:1).

Thanks in advance.

 

I thought of that too but it seems like there would be a more official way of doing it.

 

Thanks a lot that code works. I didn't get to reading through that page you linked to put the code did the trick. I'll use it even if I don't understand it.