EWWordLayout.m

@implementation EWWordLayout

- (CGSize)preferredSizeOfLayer:(CALayer *)layer
{
    size_t layerCount = [[layer sublayers] count];
    CGFloat totalWidth = layerCount * TILE_WIDTH + (layerCount - 1) * INTERTILE_GAP;
    return CGSizeMake(totalWidth, TILE_HEIGHT);
}

- (void)invalidateLayoutOfLayer:(CALayer *)layer
{}

- (void)layoutSublayersOfLayer:(CALayer *)layer
{
    CGRect rect = [layer bounds];
    size_t layerCount = [[layer sublayers] count];
    CGFloat totalWidth = layerCount * TILE_WIDTH + (layerCount - 1) * INTERTILE_GAP;
    CGFloat x = floor(0.5 * (rect.size.width - totalWidth));
    CGFloat y = floor(0.5 * (rect.size.height - TILE_HEIGHT));
    for (CALayer *sublayer in [layer sublayers])
    {
        // NSLog(@"putting %@ at (%f, %f)", sublayer, x, y);
        [sublayer setPosition:CGPointMake(x, y)];
        x += TILE_WIDTH + INTERTILE_GAP;
    }
}

@end

FromEWGameView.m

- (void)updateLetterTiles
{
    [gapLayers[0] removeFromSuperlayer];
    [gapLayers[1] removeFromSuperlayer];
    for (CALayer *l in letterLayers)
    {
        [l removeFromSuperlayer];
    }
    
    NSMutableArray *array = [NSMutableArray array];
    size_t j = 0;
    for (size_t i = 0; i < [[game letters] length]; ++i)
    {
        NSString *letterString = [NSString stringWithCharacters:(unichar[]){ toupper([[game letters] characterAtIndex:i]) } length:1];
        if (j < [letterLayers count] && [[[(CATextLayer *)[letterLayers objectAtIndex:j] string] string] isEqualToString:letterString])
        {
            [array addObject:[letterLayers objectAtIndex:j]];
            ++j;
        }
        else
        {
            [array addObject:[EWLayers letterLayer:letterString]];
        }
    }
    letterLayers = array;
    
    [wordLayer addSublayer:gapLayers[0]];
    for (CALayer *l in letterLayers)
    {
        [wordLayer addSublayer:l];
    }
    [wordLayer addSublayer:gapLayers[1]];
    
    NSLog(@"wordLayer sublayers: %@", [wordLayer sublayers]);
    
    [wordLayer layoutIfNeeded];
}