OMG... I was just gonna say that the one app I use CONSTANTLY is TempoSlow!
I teach dance so it's an important app for me. Nothing else comes close.
I've actually communicated with them a few times via email to have them add new features. I think I have a direct email address. I'll PM it to you if I find it.
I just left a comment on their website begging them to update for iOS 11
Funny... the Android version was updated in 2016:
https://play.google.com/store/apps/details?id=com.martianstorm.temposlowmo&hl=en
I wonder if they are giving up on the iOS version... which is a shame since 99% of the dance people I know use iPhones...
Maybe I'll pick up a cheap Android tablet or one of those burner phones just for music in class. That actually wouldn't be a bad thing since my iPhone wouldn't be tied up for music.