Unique Invisible Characters? Objective C

Question

I'm wondering if it is possible to have unique characters that cannot be seen through a label but still represent something.

So if I wrote:

12*12(2$2)
Appear as: 12*12(22)  or   12*12(2 2)

"$" would be the invisible character but then I could use the replace text function to replace it later with ** per say.

Answer 1

Maybe you can use non-breakable-space for that: @"\ " .

See http://en.wikipedia.org/wiki/Whitespace_character for a list of other whitespace characters.