Why does my view become white when i remove a subview?

in my view I have a scrollView as subview. The scrollView has another subview called thePDFView. It is for showing a PDF page.

This view has 2 subviews. drawImage is an image loaded from disk above the whole PDF view.

And paintView is the second subview where all the painting and markup is done. But I only want to add paintView when I press the paint Button.

This works, but when I press it again to stop painting mode and re开发者_StackOverflow社区move the view from superview, the whole screen gets white.

How can I bypass that?

- (id)init
{
  ...
  [self.view addSubview:theScrollView];
  [theScrollView addSubview:thePDFView];

  drawImage = [UIImage imageWithData:retrievedData];
  [thePDFView addSubview:drawImage];

  paintView = [[PaintViewController alloc] initWithImage:drawImage andPath:pageString];
}

- (void) togglePainting:(NSNotification *)notif  {

if (!painting) {
    theScrollView.scrollEnabled = false;
    [thePDFView addSubview:paintView.view];
}
else {
    theScrollView.scrollEnabled = true;
    [thePDFView removeFromSuperview];
}

painting = !painting;
}

[thePDFView removeFromSuperview]; 

removes the whole view which was inside the scroll view leaving you nothing but the scrollview which does not have any subviews now. Hence your view is white. I think you wanted to remove only paintView.view so it should be [paintView.view removeFromSuperview];