Elise,
I'm sorry, but I don't think I will ever create an iPhone version of Custom Maps. Apple does not like free apps created as a hobby.
To create an iPhone version, I would need to buy a ~$1,500 Macbook laptop, a ~$1,000 iPhone, and pay annually ~$100 to Apple to keep the app in their Play Store. And I would need to spend a few months of my time to convert Custom Maps to some Apple approved programming language. And I would need to create separate versions for phones and tablets, and possibly even different versions of the iOS.
Considering all that I hope you understand why I will not be creating an iPhone version of the app.