Getting ready for my trip!

Now that the school year is finally over, I can focus on preparing for my trip to Madrid!  Figuring out how to use my iPhone 5 abroad is trickier than I thought.  After talking to most people, I heard that getting a local SIM card in Madrid will be easiest.  Does anyone have thoughts on that?  Gracias!

This is from my trip to Bilbao, Spain a few years back!