Math parsing libraries can be extremely useful whenever you want to evaluate a complex mathematical expression. In Objective-C you can use NSPredicate. If you want to extend the functionality of NSPredicate however, this can be extremely difficult.
I came across a math parser that provides many advantages over NSPredicate, and other existing math libraries with in my opinion the key feature being the ease at which you can register new functions.
The library is DDMathParser from DaveDeLong. The Github for the library can be found here:
You can also read Dave’s extensive writeup on the library on his website here:
Parsing Mathematical Expressions
There are many other advantages of using Dave’s library over NSPredicate and other existing math parser’s in his writeup.
Looks like the right choice if you need to go beyond the default functionality provided by NSPredicate.