Where can I learn to make an iOS app?

I have some experience with making games for Mac & Windows, and I mainly use C#.

I want to make an app, but not a mobile game. I want to make an app in which the user has to complete a routine, with one activity done every day. Where can I learn to do this?

Which part do you need to learn?

Well, I’ve never made an app before, so any tutorial would help me, I guess.

Try Unity’s Learn section.