In your Main. storyboard Add a
Using stack view, add 17 buttons:
Numbers 0 through 9 (10 buttons)
Decimal point (.) (1 button)
Operations (+, -, *, /) (4 buttons)
Equality sign (=) (1 button)
All clear (AC) to clear the functions/contents in the label (1 button)
In your ViewController. swift file add appropriate outlets and actions to your above created objects.
All the buttons should have appropriate text and action. For example: Numbers should append appropriate number to the label, Equality sign should replace the label content with the result.
Your label must show the entire expression before the result is calculated (i. e. before the equality button is tapped.)
For example: With this sequence of button taps, 1, + and 2, your label must show "1", "1+" and "1+2" for each corresponding button tap. The label must be replaced with "3" when tapped on =.

Change the background color of the label depending on the result
If the result is negative, change the background color of the label to
Since you will be converting the label string into an expression and perform the calculation, you will get errors for improper expressions. Handle that error, set the result in the label to 0 and change the background of the label to
For a calculated non-negative result, the background color of the label should be a default color (same color when the app is launched). The default is usually white, but you can choose any color other than black and
Make sure the text within the label is visible when the background color is changed (i. e. change the text color appropriately if the text is )