Image IO - iOS Core Animation - page 298

forIndexPath :indexPath];
//add the tiled layer
CATiledLayer *tileLayer = [cell. contentView . layer . sublayers lastObject ];
if (!tileLayer)
{
tileLayer = [ CATiledLayer layer ];
tileLayer. frame = cell. bounds ;
tileLayer. contentsScale = [ UIScreen mainScreen ]. scale ;
tileLayer. tileSize = CGSizeMake (
cell. bounds . size . width * [ UIScreen mainScreen ]. scale ,
cell. bounds . size . height * [ UIScreen mainScreen ]. scale );
tileLayer. delegate = self ;
[tileLayer setValue : @( indexPath. row ) forKey : @"index" ];
[cell. contentView . layer addSublayer :tileLayer];
}
//tag the layer with the correct index and reload
tileLayer. contents = nil;
[tileLayer setValue : @( indexPath. row ) forKey : @"index" ];
[tileLayer setNeedsDisplay ];
return cell;
}
- ( void )drawLayer:( CATiledLayer *)layer inContext:( CGContextRef )ctx
{
//get image index
NSInteger index = [[layer valueForKey : @"index" ] integerValue ];
//load tile image
NSString *imagePath = self . imagePaths [index];
UIImage *tileImage = [ UIImage imageWithContentsOfFile :imagePath];
//calculate image rect
CGFloat aspectRatio = tileImage. size . height / tileImage. size . width ;
CGRect imageRect = CGRectZero ;
imageRect. size . width = layer. bounds . size . width ;
imageRect. size . height = layer. bounds . size . height * aspectRatio;
imageRect. origin . y = (layer. bounds . size . height - imageRect. size . height )/ 2 ;
//draw tile
UIGraphicsPushContext (ctx);
[tileImage drawInRect :imageRect];
UIGraphicsPopContext ();