In every program, you can design the unique features of your program while letting the Cocoa framework worry about making your program look and behave like a standard macOS program. To create the common features of nearly every macOS program, you can use alerts and panels.
An alert typically pops up on the screen to inform the user, such as asking the user to verify the deletion of a file or to alert the user of a problem. A panel displays common user interface items such as a print panel that macOS programs typically display to give you options for printing, or an open panel ...
