What are the limitations of an iPhone that prevent one from creating a nds emulator on it?

I've read that there are too many buttons that are required for playing most games that the iPhone cannot accommodate for. Additionally, is the even iPhone powerful enough for a DS emulator? Thanks.

This contains some info on the topic but its not开发者_如何学C very comprehensive. http://forums.macrumors.com/archive/index.php/t-267942.html

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Whether it's powerful enough or not isn't really relevant - Apple's app store terms prohibit emulators:

3.3.2 An Application may not itself install or launch other executable code by any means, including without limitation through the use of a plug-in architecture, calling other frameworks, other APIs or otherwise. No interpreted code may be downloaded or used in an Application except for code that is interpreted and run by Apple's Documented APIs and builtin interpreter(s).