This repo contains the source code for an iPhone-App named "Calculator", which is my work on Assignment 1 and 2.
I've developed it as member of the Stanford University class "Coding together-Apps for iPhone & iPad" (CS193p). This class has been setup by Standford University in summer 2012 as an online peer collaboration community on piazza.com. Moderated by instructors, members can communicate about iOS development issues in order to finish their given assignments.
The Coding-together class is based on lectures Developing Apps for iOS (CS193P) from Prof. Paul Hegarty, that are distributed online via iTunes U.
The requested features for the App are defined in the class's Assignments 1 and 2. There are mandatory and optional requests, that give extra credits in the "real world".
The main task was to develop a single-view app for iPhone (>= iOS 5.x), that works as a RPN-Calculator. "RPN" stands for "Reverse Polish notation". This is some old-fashioned stuff of the early days of digital calculators (-> Wikipedia article).
Assignment 2 is based on the code for Assignment 1. I've added these features in accordance with Assignment 1:
- enhance the calculator to be programmable.
- new variable buttons for entering variables named "x", "a" and "b".
- new test buttons for applying (hard coded) values to the variables.
- new variable display in the view to display the variable with values, which are used in the current program.
- changed the history label to show the program entered by a user in a more convenient way with outbreaking minimization of the use of parentheses.
- new undo button as an enhancement to the formerly backspace button: when there is no last digit to be deleted, the user can delete the last operation or operand from the program stack.
Extra Credit:
- enhanced error handling: now displaying an error message instead of a Zero-Number, when an error occured during run of the program (e.g. division by zero).
- It's a great enhancement of user experience, especially in combination with the new undo feature (see above).
Additional features on my own:
- tweaked buttons to be more userfriendly (only in the view, history display remains unchanged).
- new logo images for app.
- new golden background image for the main calculator view.
- new 1/x button delivers functionality to calculate reversal numbers.
- enhanced error handling by displaying a smiley in the history label, when an operand was missed by the last operation (instead of the formerly "0" in this situation).
- major feature: support for device rotation is added including a new view for landscape mode, done by major improvements in Storyboard and CalculatorView.m.
I've implemented all of those features, e.g.:
- a history label, that displays the operands and operations pushed onto the calculator stack. A "="-character indicates, that the main display is representing the result of an operation.
- provide digit buttons for the user input of numbers.
- provide an enter button to push the current display number onto the calculator stack.
- provide operation buttons to let the user perform math operations (+, -, /, *).
- provide additional operation buttons like sin, cos, log, √, x²
- provide period button and handle input of decimal delimiter properly.
- provide +/- button to change the leading sign. If user is entering a number, switch the sign of the main display. Else handle it like an operator, to math the last operation's result by * (-1).
- provide π button to enter Pi and push it onto the calculator stack.
- rror handling has to be done not by an error indicator, but by delivering "0" as an operation's result, e.g. when division "/0" gets calculated.
- backspace button to delete the last digit of a number, that the user currently is entering.
Additional features on my own:
- provide logo image for app.
- provide image backgrounds for buttons and history/main display label.
History:
- Assignment 1: "RPN-Calculator"
- Assignment 2: "Programmable Calculator"
- Assignment 3: "Universal App"