Catching NSInvalidArgumentException from NSExpression

Question

In my code I am evaluating strings as mathematical expressions for example:

NSString *formula=@\"9*7\";
NSExpression *expr =[NSExpression expressionWithFormat:fo         


        

Answer 1

What you need is a maths parser. NSExpression was designed to take well-formed input, and doesn't handle errors. A quick Google will give this.