Provides RPL (Reverse Polish Notation) calculator, where numbers are entered first then operations. For example, to add 6 and 4, you would:
6 Enter, 4 Enter, + or 6 Enter, 4 +
This assignment solution covers all the required tasks including the ones listed under extra credit. Solution is Swift 2.0 and iOS 9.0 compatible.
1. Overloaded the enter function for user input, because we want add to add it the history. The enter function is also called from other places in the code where we don’t want to add to history.
2. As mentioned in the assignment hints, floating point implementation was possible to add with a single-line of code:
if (digit != ".") || (digit == "." && display.text!.rangeOfString(".") == nil)
3. Pi implementation does not use the performOperation function but inline code since it’s easy to add:
case "π": displayValue = M_PI; enter()