Sorting

static NSComparator upComparator = ^NSComparisonResult(id obj1, id obj2) {
	if ([obj1 position].y < [obj2 position].y) {
		return NSOrderedAscending;
	} else if ([obj1 position].y > [obj2 position].y) {
		return NSOrderedDescending;
	} else {
		return NSOrderedSame;
	}
};

static NSComparator rightComparator = ^NSComparisonResult(id obj1, id obj2) {
	if ([obj1 position].x > [obj2 position].x) {
		return NSOrderedAscending;
	} else if ([obj1 position].x < [obj2 position].x) {
		return NSOrderedDescending;
	} else {
		return NSOrderedSame;
	}
};
	
static NSComparator downComparator = ^NSComparisonResult(id obj1, id obj2) {
	if ([obj1 position].y > [obj2 position].y) {
		return NSOrderedAscending;
	} else if ([obj1 position].y < [obj2 position].y) {
		return NSOrderedDescending;
	} else {
		return NSOrderedSame;
	}
};
	
static NSComparator leftComparator = ^NSComparisonResult(id obj1, id obj2) {
	if ([obj1 position].x < [obj2 position].x) {
		return NSOrderedAscending;
	} else if ([obj1 position].x > [obj2 position].x) {
		return NSOrderedDescending;
	} else {
		return NSOrderedSame;
	}
};
	
switch ([self gravity])
{
	case DirectionUp: [[self cubes] sortUsingComparator:upComparator]; break;
	case DirectionRight: [[self cubes] sortUsingComparator:rightComparator]; break;
	case DirectionDown: [[self cubes] sortUsingComparator:downComparator]; break;
	case DirectionLeft: [[self cubes] sortUsingComparator:leftComparator]; break;
	default: HDFail(@"Invalid direction", HDFailureLevelFatal);
}