gistfile1.h

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^(void)
   {
	   // take snapshot of main view to fake background
	   //
	   // start with a vertical slice of the middle, slightly taller than modal
	   //
	   
	   // translate & clip layer before rendering for performance
	   //
	   CGContextRef c = CGBitmapCreateSomethingSomething(args);
	   CGContextTranslateCTM(c, (baseView.bounds.size.width - 540) / -2, 0);
	   CGContextClipToRect(c, CGRectMake((baseView.bounds.size.width - 540) / 2, 0, 540, baseView.bounds.size.height - ((baseView.bounds.size.height - 620) / 2)));
	   
	   // render to context
	   //
	   [baseView.layer renderInContext:UIGraphicsGetCurrentContext()];
	   
	   CGImageRef	imageRef = CGBitmapCreateImagePlease(c);
	   CGContextRelease(c);
	   
	   // set image from it
	   //
	   dispatch_saync(dispatch_get_main_queue(), ^(void)
	   {
	   	backgroundImageView.image = [UIImage imageWithCGImage:imageRef];
	   	CGImageRelease(imageRef);
	   	);
   });