Fitbit updated its iOS app to allow users without a One, Flex or Force tracker to keep an eye on their fitness activities. Relying on the M7 motion co-processor found in the iPhone 5s, the feature called MobileTrack can be used for basic step, distance and calorie tracking parsed from the phone itself, rather than a dedicated wristband.
There other apps that can serve the same purpose, but the point here is to bring more users to the Fitbit community. And eventually hope that some of them will end-up buying the popular wristband to expand their tracking capabilities.
In addition, Fitbit for iOS version 2.1 also comes with redesigned sections for silent alarms, profiles, tracker settings and sign-up/sign-in.