When visiting Tallinn we brought only our iPhones to take pictures. But using the touch screen was quite a challenge facing minus 15 degrees Celcius. Jaco likes challenges, so he found a way :-)
A tutorial on how to take pictures with your iPhone when it's freezing cold.
You could of course forget all this and just buy really cool hand knitted iPhone mittens like Aline did. They have a special flap to cover your fingers when you are not using your iPhone.
Actually the nice old lady who made them didn't have this purpose in mind, she was wearing a pair to keep her fingers warm in between sales. Guess all good designs are multifunctional :-)