I made one for Android and iOS and submitted it to the Appstore; probably they won't accept it though as it's 'too simple'? (Mine is free, no ads, I just wanted it for myself)

There is a paid one here from someone which looks quite nice: https://itunes.apple.com/us/app/7-minute-workout/id650762525...

Mine is here: https://play.google.com/store/apps/details?id=com.vafive.sev...

And waiting for an Appstore response as well.