static unsafe extern void RemoveObserver(CFNotificationCenterRef center, IntPtr observer, CFNotificationCallback callback, IntPtr name, IntPtr obj);
static extern unsafe void RemoveObserver(CFNotificationCenterRef center, IntPtr observer, CFNotificationCallback callback, IntPtr name, IntPtr obj);
static unsafe extern void AddObserver(CFNotificationCenterRef center, IntPtr observer, CFNotificationCallback callback, IntPtr name, IntPtr obj, CFNotificationSuspensionBehavior suspensionBehavior);
static extern unsafe void AddObserver(CFNotificationCenterRef center, IntPtr observer, CFNotificationCallback callback, IntPtr name, IntPtr obj, CFNotificationSuspensionBehavior suspensionBehavior);