can I convert + as an NSString to addition operator directly?

Question

I have a mathematical equation in string format.

Is there a way to convert @"+"(String constant) directly to addition operator in objective C Or

I have to use If-Else statements to solve this equation ??

Answer 1

NSPredicate * parsed = [NSPredicate predicateWithFormat:@"123+456+678-985 = 0"];
NSExpression * left = [(NSComparisonPredicate *)parsed leftExpression];
NSNumber * result = [left expressionValueWithObject:nil context:nil];
float i = [result floatValue];