Creating a CGImage from a CALayer tree.

CALayer+CGImage.m

CGSize imageSize = CGSizeMake(1000, 1000);

CGColorSpaceRef colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);

CGContextRef theContext = CGBitmapContextCreate(NULL, imageSize.width, imageSize.height, 8, 4*imageSize.width, colorSpace, kCGImageAlphaPremultipliedLast);
    
[layerView.layer renderInContext:theContext];

// Layer tree has backgroundFilters set on some of the CALayers
// When it's rendered in the Bitmap Context, none of these filters are applied.

CGImageRef CGImage = (CGBitmapContextCreateImage(theContext);

// Can no do this, but no point cause filters have already NOT been applied.
// CIImage* image = [CIImage imageWithCGImage:CGImage];

// Was hoping to find a way to get a CALayer hierarchy to provide content for a CIImage and inside a CIContext
// to ensure that the CIFilters are applied correctly
// Currently looking into CARenderer