Plenty of people use their iPhone or Android smartphone to view and follow workouts. Thanks to the Perchmount iPhone Dumbbell Mount, you can attach your phone to weights, bars, and exercise bikes. It has a clamp that fits bars up to 1.5″ in diameter.
This iPhone fitness mount can be attached to a wide variety of exercise machines and tools. You can rotate your phone 360-degrees to use it in portrait or landscape mode. It is pretty lightweight and small, so you can take it with you anywhere. More info is available here.