Anyone done an Objective-C Xode version of Osherove´s TDD Kata “String Calculator”?

Question

Always trying to code better and I am interested in doing TDD for Objective-C and Xcode.
Do you know any post that implement something like Roy Osherove´s "String Calculator"-Kata

Update: trying to find out how to speed up TDD on iOS

Answer 1

I did that. You can find the screencast and the Xcode project here in my blog. I’ve written the text around it in german, but you should have no trouble playing the video or finding the download link.

Answer 2

I'd use NSPredicate like this:

NSPredicate * parsed = [NSPredicate predicateWithFormat:@"6 * 7 = 0"];
NSExpression * left = [(NSComparisonPredicate *)parsed leftExpression];
NSNumber * result = [left expressionValueWithObject:nil context:nil];
NSLog(@"result: %@", result);

Look here for more info on using NSPredicate in weird ways.