Screen capture in Cocoa (Grabs the screen contents and puts it into a NSImage)

ScreenCapture.m

NSImage *CaptureScreen() {
  
  // Get the Screen Rect
  NSRect screenRect = [[NSScreen mainScreen] frame];
  
  // Create a CGImage with the screen contents
  CGImageRef cgImage = CGWindowListCreateImage(screenRect, kCGWindowListOptionOnScreenOnly, kCGNullWindowID, kCGWindowImageDefault);
  
  // Convert the CGImage into a NSBitmapImageRep
  NSBitmapImageRep *rep = [[NSBitmapImageRep alloc] initWithCGImage:cgImage];
  
  // Release the CGImage
  CGImageRelease(cgImage);
  
  // Create a NSImage
  NSImage *image = [[NSImage alloc] init];
  
  // Add the NSBitmapImageRep
  [image addRepresentation:rep];

  return image;
}