Please note, this blog entry is from a previous course. You might want to check out the current one.
Rename the ViewController class you’ve been working on in Assignments 1 and 2 to be CalculatorViewController.
Rename the filename, by selecting the filename and clicking one additional time:
Inside the file change the class name:
class CalculatorViewController: UIViewController
Choose the new class name in the inspector of the view controller in story board:
The complete code for the task #2 is available on GitHub.