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    <p>In the example you show, I don't believe they're showing a background through the view. I think they're simulating a background in core graphics. In other words, in each cell they draw a light gray color for the background. They then draw the shadow (using transparency), and finally they draw the rest of the opaque content on the top. I could be wrong, but I don't believe you can make portions of the view transparent. If so, I'd be very, very interested in it because I use core graphics all the time, but I avoid rounded corners because blending the entire view for it just doesn't seem to be worth it.</p> <p><strong>Update</strong></p> <p>After doing some more research and looking through Apple's docs, I don't believe it's possible for only part of a view to be opaque. Also, after reading through Twitter's blog post, I don't think they are saying that they did so. Notice that when they say: </p> <blockquote> <p>Instead, our Tweet cells contain a single view with no subviews; a single drawRect: draws everything.</p> </blockquote> <p>They were specifically talking about <code>UILabel</code> and <code>UIImageView</code>. In other words, instead of using those views they're drawing the image directly using Core Graphics. As for the UILabels, I personally use Core Text since it has more font support but they may also be using something simpler like NSString's <code>drawAtPoint:withFont:</code> method. But the main point they're trying to get across is that the <em>content</em> of the cell is all one CG drawing.</p> <p>Then they move to a new section: <strong>Avoid Blending</strong>. Here they make a point of saying that they avoid blending by:</p> <blockquote> <p>splitting the shadow areas from content area of the cell.</p> </blockquote> <p>The only way to do this is to use different views. There are two approaches they could be using, but first note that the cell dividers are themselves overlays (provided by the tableView). The first way is to use multiple views inside the cell. The second way is to underlay/overlay the shadows/blended-views behind/over the cells by inserting the appropriate views into the UIScrollView. Given their previous statement about having only one view/drawRect for each cell, this is probably what they're doing. Each method will have its challenges, but personally I think it would be easier to split the cell into 3 views (shadow, content, shadow). It would make it a lot easier to handle first/last cell situations. </p>
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    1. POCoreGraphics - Blending only *part* of a view
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    1. USAaron Hayman
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    1. COSure I can draw gradients and transparent colors, but in the Tweet cell the shadows are on the edges and let the background show through. This implies that the view that I'm drawing them into is *non* opaque, otherwise you would see a black background behind the shadows instead of the view behind them.
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    2. COI don't think they're showing through a background. I think they're simulating a background in their cell view. I'll update my answer to explain.
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    3. COThe article states: "Tweets have a drop shadow on top of a subtle textured background. This presented a challenge, as blending is expensive." -- If they are only *simulating* a background, then they wouldn't need to blend anything at all and the entire cell view would be green when you toggle "Color Blended Layers".
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