CGLayerRef turns out empty only in OS X 10.11 (El Capitan) - objective-c

Question

I have an image editing application, that has been working through 10.10, but in 10.11 a bug came up
When I view a CIImage created w/ -imageWithCGLayer, it shows as an empty image (of the correct size) only in 10.11
CGSize size = NSSizeToCGSize(rect.size);
size_t width = size.width;
size_t height = size.height;
size_t bitsPerComponent = 8;
size_t bytesPerRow = (width * 4+ 0x0000000F) & ~0x0000000F; // 16 byte aligned is good
size_t dataSize = bytesPerRow * height;
void* data = calloc(1, dataSize);
CGColorSpaceRef colorspace = [[[_imageController document] captureColorSpace] CGColorSpace];
CGContextRef bitmapContext = CGBitmapContextCreate(data, width, height, bitsPerComponent, bytesPerRow, colorspace, kCGImageAlphaNone | kCGBitmapByteOrder32Host);
CGLayerRef canvasLayer = CGLayerCreateWithContext(bitmapContext, scaledRect.size, NULL);
[self drawCanvasInLayer:canvasLayer inRect:scaledRect];
CIImage *test = [CIImage imageWithCGLayer:canvasLayer];
NSLog(#"%#",test);
So when I view CIImage *test on 10.10, it looks precisely as I want it. On 10.11 it is a blank image of the same size.
I tried looking at the API diffs for CGLayer & CIImage but the documentation is too dense for me. Has anybody else stumbled across this issue? I imagine it must be something w/ the initialization of the CGContextRef, because everything else in the code is size related

Answer 1

That particular API was deprecated some time ago and completely removed in macOS 10.11. So your results are expected.
Since you already have a bitmapContext, modify your -drawCanvasInLayer: method to directly draw into the bitmap and then create the image using the bitmpap context thusly,
CGImageRef tmpCGImage = CGBitmapContextCreateImage( bitmapContext );
CIImage* myCIImage = [[CIImage alloc] initWithCGImage: myCIImage];
Remember to do CGImageRelease( tmpCGImage ) after you are done with your CIImage.
I recently solved this very problem and posted a sample objective-C project to work around the loss of this API.
See http://www.blinddogsoftware.com/goodies/#DontSpillTheBits
Also, don't forget to read the header file where that API is declared. There is very often extremely useful information there (in Xcode, Command+click on the specific API)