Swift - “use of unresolved identifier”

Question

I am studying Swift! I want create Main interface on xib. But have error \"use of unresolved identifier\".

Add code from MainViewController

Answer 1

You likely didn't add the class to the target. Click on the MainViewController class and open the utilities tab on the upper right corner in Xcode:

Make sure the appropriate target is checked.

EDIT: Apparently you don't have target membership there - which is bizarre in and of itself. Try re-creating the MainViewController class from scratch and make sure the correct target is selected: