Posted when the window’s occlusion state changes.
- macOS 10.9+
The notification object is the
NSWindow object whose occlusion state has changed. This notification does not contain a
This notification indicates a change in the window’s occlusion state; it doesn’t indicate a change in the occlusion region. When you receive this notification, you can get the window’s current occlusion state and—based on the result—you may want to increase responsiveness and save power by halting expensive operations that the user can’t see.