June 2011
Intermediate to advanced
590 pages
19h 31m
English
Content preview from iOS Programming: The Big Nerd Ranch Guide, Second EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Challenge: Dynamic Layer Content
Give boxLayer a delegate to draw its content. When the layer is near the top of the screen, draw the Hypno.png image to the layer in the delegate method with full opacity. As the layer approaches the bottom of the screen, draw the image more transparently.
This is a very difficult challenge, so you can have three hints:
- The delegate of boxLayer cannot be HypnosisView.
- You must send setNeedsDisplay to the layer every time it changes position.
- To set the opacity of drawing in a context, use the function CGContextSetAlpha.
Happy coding!
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.