CGImageRef image = (__bridge CGImageRef)self.view.layer.contents;
    CGDataProviderRef dataProviderRef = CGImageGetDataProvider(image);
    CFDataRef dataRef = CGDataProviderCopyData(dataProviderRef);
    void *dataBytePointer = (void *)CFDataGetBytePtr(dataRef);
    CGColorSpaceRef colorSpace = CGImageGetColorSpace(image);
    CGContextRef context = CGBitmapContextCreateWithData(dataBytePointer, CGImageGetWidth(image), CGImageGetHeight(image), CGImageGetBitsPerComponent(image), CGImageGetBytesPerRow(image), colorSpace, CGImageGetBitmapInfo(image), NULL, NULL);
    CGContextDoWhatever(context)...