How to make any electronic device waterproof!

So a couple of days ago I found myself driving my niece to her swimming classes, she wanted to be filmed so she could show her mother how good she was. The only thing I could film with was my iPhone but seeing the water splashing everywhere I though it wouldn't be very cautious to start filming with it. So I decided to improvise, I went to the bathroom took a condom from my wallet (you should always have a condom with you, you know, just in case ;P) and put it on the phone and tied a knot to seal it. I couldn't take a picture but here's a picture I found online of a camera. Hope this helps
-Roger