Since BuggyCalc has crashed, and Xcode has brought itself to the foreground with the Debug area displayed, we can take this opportunity to look at some of the information that is available in the debugger:
Look more closely at the Debug area. You will see it has two panes. On the left-hand side is the variable view and on the right-hand side is the console as shown in the following screenshot:
By looking in the variable view, we can see the actual values that are in our variables when the program ended up in the debugger.
Drag the top of the Debug area up, to make the view larger.
Click on the disclosure triangle beside self to display all the member variables for our AppDelegate as shown in the following screenshot: