STEP does not have an iPhone app. STEP is available as an app for Android, and via web browser for other types of phones. 

We are hoping to release an iPhone app in the next financial year. We are also working on improvements to our Speech interface so that it will work smoothly on iOS Safari and Chrome browsers.

When we launched STEP in August 2016, 90% of our mobile traffic was from Android devices. We therefore prioritized Android. Please continue to be patient while we work towards a release date announcement for iOS. 

We sincerely appreciate the enthusiasm of iPhone users for STEP.