title: trying to draw scaled UIImage in custom view, but nothing's rendering
body: <p>I've created a custom view class and right now just want to draw an image scaled to fit the view, given a UIImage.  I tried just drawing the UIImage.CGImage, but as others have attested to on this site (and in the docs), that renders the image upside down.</p>
  
  <p>So, at the suggestion of an answer I found to another question, I'm trying to draw it directly, but nothing is rendering in the view and I'm not sure why.  Here's my drawing code:</p>
  
  <pre><code>- (void)drawRect:(CGRect)rect {
      // Drawing code
      [super drawRect:rect];
  
      if (self.originalImage) {
          [self drawImage];
      }
  }
  
  - (void) drawImage {
      if (CGSizeEqualToSize(originalImage.size, self.frame.size) == NO) {
          CGFloat scaleFactor = 1.0;
          CGFloat scaledWidth = 0.0;
          CGFloat scaledHeight = 0.0;
          CGPoint thumbPoint = CGPointMake(0.0, 0.0);
  
          CGFloat widthFactor = self.frame.size.width / originalImage.size.width;
          CGFloat heightFactor = self.frame.size.height / originalImage.size.height;
  
          if (widthFactor &lt; heightFactor) {
              scaleFactor = widthFactor;
          } else {
              scaleFactor = heightFactor;
          }
  
          scaledWidth = originalImage.size.width * scaleFactor;
          scaledHeight = originalImage.size.height * scaleFactor;
  
          if (widthFactor &lt; heightFactor) {
              thumbPoint.y = (self.frame.size.height - scaledHeight) * 0.5;
          } else if (widthFactor &gt; heightFactor) {
              thumbPoint.x = (self.frame.size.width - scaledWidth) * 0.5;
          }
  
          UIGraphicsBeginImageContext(self.frame.size);
          CGRect thumbRect = CGRectZero;
          thumbRect.origin = thumbPoint;
          thumbRect.size.width = scaledWidth;
          thumbRect.size.height = scaledHeight;
  
          [originalImage drawInRect:thumbRect];
          self.scaledImage = UIGraphicsGetImageFromCurrentImageContext();
          UIGraphicsEndImageContext();
      } else {
          self.scaledImage = originalImage;
      }   
  }
  </code></pre>
  
  <p>My understanding (after studying this a bit) is that the UIGraphicsBeginImageContext function creates an <em>offscreen</em> for me to draw into, so now how do I render that context on top of the original one?</p>