Objective-C code for toggling Do Not Disturb on macOS (including Big Sur)

macosDND.m

/// Turn Do Not Disturb on or off
/// Only handles on and off, no schedules
/// @param enabled true on, false off
- (void)setDND:(BOOL)enabled {
	NSLog(@"Turning Do Not Disturb %@", (enabled ? @"on" : @"off"));
	if (@available(macOS 11.0, *)) {
		NSUserDefaults * defaults = [[NSUserDefaults alloc] initWithSuiteName:@"com.apple.ncprefs"];
		NSData * subPlistData = [defaults objectForKey:@"dnd_prefs"];

		NSMutableDictionary * propertyListDict = [[NSPropertyListSerialization propertyListWithData:subPlistData options:0 format:nil error:nil] mutableCopy];

		NSDictionary * userPrefs;

		if (enabled) {
			userPrefs = @{
				@"enabled": @YES,
				@"date": [NSDate now],
				@"reason": @1
			};
		} else {
			userPrefs = @{};
		}

		[propertyListDict setObject:userPrefs forKey:@"userPref"];
		subPlistData = [NSPropertyListSerialization dataWithPropertyList:propertyListDict format:NSPropertyListBinaryFormat_v1_0 options:0 error:nil];

		[defaults setObject:subPlistData forKey:@"dnd_prefs"];

		// Sync preferences and restart usernoted to update the UI
		CFPreferencesSynchronize(CFSTR("com.apple.ncprefs"), kCFPreferencesCurrentUser, kCFPreferencesCurrentHost);
		[NSTask launchedTaskWithLaunchPath:@"/usr/bin/killall" arguments:@[@"usernoted"]];
		// The following seems to be unnecessary. Reports say it might be needed first
		// time after a reboot, but not confirmed.
		// [NSTask launchedTaskWithLaunchPath:@"/usr/bin/killall" arguments:@[@"ControlCenter"]];
	} else {
		// Modify global preferences on everything prior to Big Sur
		CFPreferencesSetValue(CFSTR("dndStart"), (enabled ? (__bridge CFPropertyListRef)(@(0.0f)) : NULL),
													CFSTR("com.apple.notificationcenterui"),
													kCFPreferencesCurrentUser, kCFPreferencesCurrentHost);

		CFPreferencesSetValue(CFSTR("dndEnd"), (enabled ? (__bridge CFPropertyListRef)(@(1440.f)) : NULL),
													CFSTR("com.apple.notificationcenterui"),
													kCFPreferencesCurrentUser, kCFPreferencesCurrentHost);

		CFPreferencesSetValue(CFSTR("doNotDisturb"), (__bridge CFPropertyListRef)(enabled ? @(YES) : @(NO)),
													CFSTR("com.apple.notificationcenterui"),
													kCFPreferencesCurrentUser, kCFPreferencesCurrentHost);

		// Notify all the related daemons that we have changed Do Not Disturb preferences
		CFPreferencesSynchronize(CFSTR("com.apple.notificationcenterui"), kCFPreferencesCurrentUser, kCFPreferencesCurrentHost);
		[[NSDistributedNotificationCenter defaultCenter] postNotificationName:@"com.apple.notificationcenterui.dndprefs_changed" object:nil userInfo:nil deliverImmediately:YES];
	}
}