Invalidates a CFRunLoopObserver object, stopping it from ever firing again.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
- Core Foundation
The run loop observer to invalidate.
observer will never fire and call its callback function again. This function automatically removes
observer from all run loop modes in which it had been added. The memory is not deallocated unless the run loop held the only reference to