Spinning pinwheel

[1] Officially, the macOS Human Interface Guidelines refer to it as the spinning wait cursor,[2] but it is also known by other names.

Apple's HyperCard first popularized animated cursors, including a black-and-white spinning quartered circle resembling a beach ball.

Other applications provided their own theme-appropriate custom cursors, such as a revolving Yin Yang symbol, Fetch's running dog, Retrospect's spinning tape, and Pro Tools' tapping fingers.

[9] In OS X 10.10, the entire pinwheel rotates (previously only the overlaying translucent layer moved).

In single-task operating systems like the original Macintosh operating system, the wait cursor might indicate that the computer was completely unresponsive to user input, or just indicate that response may temporarily be slower than usual due to disk access.

After the transition to Mac OS X (macOS), the display of the wait cursor was only able to be controlled by the operating system, not by the application.

This could indicate that the application was in an infinite loop, or just performing a lengthy operation and ignoring events.

Another approach is to divide the work into smaller packets and use NSRunLoop or Grand Central Dispatch.

Along with its other functions, it allows the user to monitor and sample applications that are either not responding or performing a lengthy operation.