The Mozilla Firefox browser will not be coming to iOS unless Apple changes the way they approach third-party browsers said Mozilla vice president of product Jay Sullivan at an SXSW panel. Mozilla pulled the Mozilla Firefox Home from the Apple App Store in September 2012 and they are not building a version of the Firefox browser for iOS.
Mozilla is working on a mobile operating system of their own called Firefox OS, which will be implemented into lower end smartphones. Currently Apple enforces iOS users to work with the Apple Safari browser as the default. However you can download the Google Chrome and Opera browser from the App Store.