Well. I was just goofing around on web when I found there is no native API on iOS which lets you create rich text editor while its available for mac SDK.
I looked around a lot whether there are any libraries budding up . There is one called OMNI group rich text library, they have done a good job. They are developing more features in it.
There are people countable on finger who have actually talked about this on their blog. One blog is really recommendable. They have have been able to create the multi colored text along with the pointer. LINK TO ARTICLE.
There is a new app launched recently called Essay which is a rich text editor for iOS, but sadly there aren't very great reviews about it either. I haven't used it myself to I have to depend on the opinion of the reviewers.And also its not open source so its of no help to other developers. LINK TO ARTICLE.
And So I decided to take a plunge myself and see what good I can come up with.
Check out THIS POST of mine. I have been able to do some work on it.