Remove all test buttons and variable buttons except "x", remove variables label.
Embed CalculatorViewController in a NavigationController.
Add Graph button that segues to GraphViewController.
Add GraphViewController.
Add GraphView, create outlet to programLabel in GraphViewController.
Implement prepareForSegue:sender: in CalculatorViewController.

Display current program in programLabel within GraphViewController.
Only display equation for graph if non-empty.
Set GraphViewController as dataSource delegate for GraphView.
Implement drawRect: for GraphView.
Add AxesDrawer at scale 1.0.
Enable graph scaling, and control of scale with pinch gesture.
Add pan gesture to move origin.
Add triple-tap gesture to move origin.
Use NSUserDefaults to preserve user-defined origin and scale, add Reset button.
Set GraphView to UIViewContentModeRedraw.
Convert to Universal application. Add separate iPad storyboard, with Graph button set up through target-action.
Set GraphViewController as UISplitViewControllerDelegate.

Set and remove barButtonItem as needed.
Implement Assignment #3 Extra Credit #1.

Draw dots at each calculated coordinate rather than connecting lines.
Use GraphViewDataSource to determine drawing style.
Use UISwitch to alternate between drawing styles.