Status of D support on iOS
d, ios
Solution
As far as I can tell it should be possible. You can use gcc to compile iOS apps and gcc supports D.
I've never used D myself and I've never replaced the default compiler in Xcode, but there is an option for it in build settings.
If I were you that's where I'd start. I don't know if there are any other steps needed to get it to work, but technically it shouldn't be any harder than using C++ on iOS, which I know is fairly common.
I hope this gives you an idea of how to go forward.
Problem
What's the current status of writing apps in D on iOS? I'm not interested in using any iOS API's, just OpenGL/SDL. Is it possible to write for iOS in D at the moment? If so, how problematic is it?