- (void)didChangeSize:(CGSize)oldSize
{
    for (Tile *tile in self.tiles)
    {
        tile.size = /* some complex calculations */;
        tile.position = /* some more complex calculations */;
    }

    for (Unit *unit in self.units)
    {
        Tile *tile = [self.tiles objectAtIndex:unit.locationIndex];
        unit.size = tile.size;
        unit.position = tile.position;
    }
}