Wouldn’t it be awesome if you could update your game’s assets while your app is running? It turns out you can, and it’s not even very complicated.
Whether you want to tweak a game setting or experiment with a variety of image styles on the fly, this will be one of the things you wish you had been using all along! Either for faster development or as a design feature for your game.
In this case, we’ll build a New York Traffic Webcam viewer with Cocos2D. You will learn how to download files to your app at runtime with the iOS SDK and cocos2d-iphone, and how to check if the file on the web server has actually been modified.
Along the way you’ll understand how to use the Mac OS X built-in web server to speed up your development by replacing game assets on the fly. By copying files to a specific directory on your Mac you can make immediate changes to your running app!
And you don’t need any experience with HTML, Apache, or any other web server or web services technology. In fact, I consider myself to be an web-illiterate because I’ve hardly done anything programming-related with web services and servers in the past.
As usual, the project is available from my LearnCocos2D github repository under the MIT License. The project’s name is Cocos2D-UpdateFilesFromWebServer. To improve readability of the article I removed error checking from the code in the article.
This quick comparison sheet gives you all the info to decide whether to use Cocos2D 1.x or Cocos2D 2.x. Contrary to most programs, a higher version number doesn’t infer “better” or “more”. There are pros and cons for both versions.
At the time of this writing the decision really only boils down to whether you want to use shaders and whether you must be able to deploy your app to 1st & 2nd generation devices. See for yourself, it’s that simple:
Cocos2D v1.x(+) compatible with all iOS devices |
Cocos2D v2.x(+) OpenGL ES 2.0 shader programs |
All other differences to this day are minor, and most new features and bugfixes have been migrated back and forth between versions. For beginners I strongly recommend using v1.x as there’s a lot more documentation available for this version. Those who have no interest in writing shader programs can also safely use the v1.x branch without missing out.
Detecting collisions on pixel-perfect boundaries is the holy grail of collision detection in 2D games. As such, it seems like the ideal, if not to say perfect, solution to collision detection in general. Yet, it’s also quite complicated and the straightforward solutions don’t perform very well until you start optimizing the code.
This first post focuses on creating a pixel mask by analyzing the raw image data, as proposed over 3 years ago by Ernesto Corvi. It’s the fastest solution if you want to test if a point collides with a pixel on an image, which also works for rotated and scaled sprites. However it does take some optimizing to speed up detecting collisions between a bounding box of a node and the pixel mask, or two pixel masks.
The alternative solution is to render the two colliding objects onto a CCRenderTexture, as developed by Dani and others on the Cocos2D forum. It is able to detect collisions of arbitrarily rotated and scaled sprites but can be expected to be noticeably slower than a pixel mask. I will discuss this solution in a future iDevBlogADay post.
The results will find their way into Kobold2D, to make the solutions readily available to all developers.
Kobold2D v1.0 is now available from the Kobold2D Download page!
This is mainly a maintenance release, I found and fixed all the bugs that had been reported, including some nasty linker issues that occurred with a preference on Snow Leopard. Kobold2D is now thoroughly tested with Xcode 4.0.2, 4.1 and 4.2 under Snow Leopard and Xcode 4.2 under Lion.
Of course the latest updates of cocos2d-iphone-extensions 0.2 and cocos3d 0.6.3 are also included.
And I can’t say it often enough: Kobold2D supports ARC (automatic reference counting) out of the box! There’s nothing you need to do! Just have Xcode 4.2 installed and start writing code without retain, release and autorelease ever again.
Forward Looking Statement
The motto for the next updates is still “Get Connected!”. I want to add more online features and update the KKGameKitHelper class with remote config support provided by AppMynx. I will evaluate ShareKit and hopefully be able to implement that with (if necessary) a reasonably simple interface for Cocos2D apps.
I also have a commercial product for iOS in development that will make sending data over the network a lot simpler. The basic idea being that if, for example, you want to synchronize a sprite’s position and rotation properties with all other devices, you simply write something like this:
identifier:@"Player1"
properties:@selector(position),
@selector(rotation),
nil];
It works with any properties (except id/pointers). Whenever one of the property values changes, its value is sent to all connected devices and assigned to the property of the local object with the corresponding “Player1″ identifier. Dead simple. And coming soon.
Learn Cocos2D Game Development with iOS 5
It’s also no coincidence that the print and PDF versions of the Learn Cocos2D Game Development book (2nd Edition) are available since a few days.
The book uses Cocos2D v1.0.1, the chapters have been significantly improved, Chapter 3 is almost a complete rewrite. There are also two new chapters discussing integration of UIKit views in a Cocos2D app, as well as adding Cocos2D to an existing UIKit app. The other new chapter is about Kobold2D and introduces Lua and Cocos3D.
Readers keep asking me when the Kindle or iBooks versions of the new edition will be out. To be honest: I don’t know. But I’m confident that there will be a Kindle version and one for iBook eventually, and I expect these to be available soon. After all the first Edition is also available through these channels, and so are most (if not all) Apress books. Plus Xmas is coming, just like most companies book publishers are eager to get their best products out the door in time for Xmas.
I took Mike Ash’s performance measuring code from 2008 with the improvements made by Stuart Carnie in early 2010 and turned that into a performance measuring project for 2012.
I know it’s still 2011, consider this a forward-looking statement. In any case, the test project is available for download, ready to run, includes Cocos2D v1.0.1 and is relatively easy to modify for your own needs. This project is also available on my github repository where I host all of the iDevBlogADay source code.
Since numbers are so dry and hard to assess, you’ll find the rest of this post garnered with charts and conclusions based on the results obtained from iPhone 3G, iPod 4 and iPad.
I have no doubt that automatic reference counting (ARC) is the next big leap forward for Objective-C since the introduction of Objective-C 2.0. ARC allows you to put the burden of memory management on the (Apple LLVM 3.0) compiler, and never think about retain, release and autorelease ever again.
Since many user’s first experiences with ARC will be trying to convert an existing app, they will learn the hard way that converting existing code to ARC is not a fire & forget operation. And since this is the Internet, there’s also a lot of assumptions, false statements and other myths revolving around ARC going around.
So here’s just about everything you need to know about ARC, and some ARC-mythbusting too.
- Development Requirements for ARC apps
- Minimum Deployment Targets for ARC apps
- Required Deployment Targets with zeroing weak references
- How to enable ARC in your project
- Compile errors after switching to LLVM 3.0
- Getting third party libraries to build with ARC
- Converting an existing app to ARC
- “Cannot Convert to Objective-C ARC”
- Fixing pointer types in C structs
- Fixing C/C++ pointer transfers with bridged casts
- Fixing NSAutoreleasePool with @autoreleasepool
- Methods you can’t call (or override) anymore
- You can still override -(void) dealloc {}
- Property naming restriction
- New Property keywords: strong and weak
- ARC forbids synthesizing a readonly property without ownership qualifier
- For experts: detecting at compile-time if ARC is enabled
- For experts: allow use of ARC keywords with ARC disabled
- Myth: ARC has not been proven reliable
- Myth: ARC takes away control over Memory Management
- ARC Reference Documentation
To put it in Apple’s words: “Taking Cocos2D to a whole new level.” I can’t brag with 200+ new features though I have a few in store that should make a big bang for no bucks! 
So, here speaketh the market crier for Kobold2D. What’s new and noteworthy about this version of Kobold2D, you ask?
Built-In Gesture Recognition
Recognizing gestures has never been this easy. No (speak: zero) iOS SDK knowledge required! All gesture recognizers provided by the iOS SDK are implemented:
Tap, Double-Tap, Long-Press, Swipe, Pan, Rotation and Pinch.
Wouldn’t it be cool if you could just check the keyboard state at any time from any class?
I’ll get to the “cool” part in a moment, first let me set the record straight on how to correctly process keyboard input in Cocos2D Mac builds: Continue reading »
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