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image manipulation

Best Resources In iOS Development – July 18th 2011

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Another excellent week to be an iOS developer, and some big news in the department of iOS game development with the release of  Cocos2D V1.0.0 and the opening of the Moai SDK beta to everyone.  Also some great open source libraries and tutorials were shared.

If you have written a tutorial, open source library or tool that you would like to share you can submit the url here.

I’ve been contacted a number of times about advertising on this site so I decided to add support for BuySellAds, and added a section for small button ads.  If interested you can check out the advertising page here.

Here are the resources from the last week in order of popularity:

Open Source: Easy Multistroke and Single Stroke Complex Gesture Recognition On iOS – A couple of great libraries if you are looking to quickly implement complex gesture within your app.

Open Source: iCade Library For Easy Integration In iOS Games – Library that allows you to easily support the iCade classic arcade box/controller for iPad.  Makes a good example if you are trying to support a specific bluetooth interfacing device.

Tutorial: Manipulating Images With Touch Gestures – A tutorial with sample code demonstrating how to add touch features for image manipulation.

Tutorial: iOS Map Kit For Beginners Guide – A getting started tutorial for those beginning with the iOS map kit including a tutorial on displaying data from XML locations on a map without using any libraries outside of those included with  the iOS SDK.

Open Source: Active Record For Core Data Library – A great open source project modeled after Ruby On Rail’s ActiveRecord for more straightforward data retrieval.

News: Cocos2D Game Engine v1.0.0 Released – News about the highly popular Cocos2D game engine finally reaching the v1.0.0 release.

Tutorial: iOS Multithreading With Grand Central Dispatch (GCD) Basics – An excellent step by step guide beginning with the basics on multithreading with iOS ‘s Grand Central Dispatch.

News: Moai SDK Game Development Kit Made Available To All – The lua based open source Moai SDK has now opened the beta for anyone to download and use.

Tutorial: Calculator App Style Glossy Buttons With Core Graphics – An explanation of the technique used to create buttons just like the calculator applications that come with iOS devices.

Tutorial: How To Use The iOS Keychain To Store Names And Passwords – A guide on using the iOS keychain in order to securely store usernames and passwords.

Thanks for reading, please bookmark and share this post!


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Manipulating UIImage Data Directly Within A C type Array

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Manipulation of image data is done within many highly successful apps on the iPhone.  What is great about these apps is that the actual algorithms are relatively simple, and by mixing a few things together you can create some interesting effects.

There is one catch, and that is in order to directly manipulate the data from a UIImage you have to jump through a few Core Graphics hoops.   In creating a photo app it took me awhile to find the actual code to let me do that seemingly simple task.

Fortunately, Brandon Trebitowski has posted a nice code snippet on his site which copies that image data directly into an array which you can then modify easily, and he has placed a tutorial along with a project showing the code in action on his website here:
Image Manipulation: Retrieving And Updating Pixel Values For A UIImage

If you’d like to learn more about image processing in general you can head over and take a look at the Image Processing Lab over at CodeProject.  While that particular tutorial uses C# you can see the algorithms for some common image filters and do some interesting things.


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