Unfortunately, IOS (Ipad,Iphone) and Android do not support Opentype. �IOS are suppose to support AAT fonts, but you won't be able to embed AAT fonts for Arabic into your application without some kind of hack. This is a well known bug, and I'm not too sure if it has been fixed. Even if it is fixed, it is rare to get a good Arabic AAT font. The one and only that I know is from SIL (as mentioned, you still can't use it to embed it into your app).
I've created a workaround to embed a font into your IOS and Android App, but it it not a standard arabic font, so it is not easily used by anyone.