I'm planning to make a Homebrew App called WiiIPAEMU - An IOS Emulator for Wii and vWii (Wii U)

[J-Will]

Where should i start?

 

[MichiS97]

I was thinking about writing a smart ass reply to this but then I remembered I asked similar questions when I was young so here is some actual advice:

By the way you're phrasing your question I'm guessing you have little or no actual programming experience.
If that is NOT the case and you're actually an experienced developer then disregard everything I'm about to type here.

If you actually are as inexperienced as I think you are then let me answer your question:
Don't. An emulator is a piece of software that, depending on the system you're trying to emulate, can be extremely complicated to develop even for a very experienced developer.
What you should start with is just some standard software development on a PC. Code some games. Tetris, Snake and the like. Use any object oriented programming language you want to, but I would personally recommend C++. Focus on memory-safe programming, try to understand the low level hardware aspects of what you're doing here.
If you feel like you've grasped the concepts for development on a PC, make the switch to developing for an embedded POSIX system. Actually, the Wii is a great example for such a system.
If you've done all that and actually have an in-depth understanding about what you're doing then you will also know where to start with building an emulator.

However, start with writing an emulator for a system which has all its hardware completely documented and this documentation publicly available. The NES or Game Boy come to mind.

Specifically for iOS, you have to keep in mind that you're looking at one of the most advanced and modern operating systems out there and also one that is entirely closed source. Developing an emulator for iOS applications is an extremely difficult task for anybody, even the most skilled developers out there.