Monday, May 3, 2010

Creating a Mobile App for the iPhone

In the coming weeks, I plan on covering the development process from start to finish. I will be talking about code organization, memory management, useful xcode features, core data, performance optimization, debugging, iterative development, and any other useful topics that I come across.

iLogMiles was approved by Apple for sale on the App store, on April 6, 2010. iLogMiles is free to download. The app quickly hit the #2 spot on the top free business apps list. The user can upgrade to the full version and purchase themes from within the free application. We utilized the Apple Store Kit framework to provide the in-app store. The Store Kit framework provides the necessary means to securely process payments from within the application. Products are identified via product identifiers. Apple clearly defines the types of products that may be sold via the Store Kit framework. More on this later but keep in mind that it is very important to read through all of the documentation.

Over the next few weeks, we will be talking about the mobile application development process. To give you some background on me, I started with C++ in 1997. At the time, I mostly used the GNU compilers on FreeBSD and Linux and Sun workshop on a SPARCstation. And for the C++ courses I was taking, Borland in a Win environment. To get up to speed on iPhone OS, I purchased the WWDC 2009 sessions and watched them all (at the gym on my iPhone). I attended the iPhone tech talk tour in San Jose and I listened to any and all of the available iPhone development podcasts (at the gym) that I could find. I poured through all of the books that I could get my hands on. I read the iPhone OS programming guides on the iPhone OS developer connection. XCode also has integrated documentation for the Apple API's. I've always used vi/vim with ctags, so I had to force myself to watch the xcode screencasts (available via third-party on the Internet). There are lots of great xcode tips out there and you can print out a summary page with all of the cute shortcuts - if you are so inclined to do so. I found it quite helpful to print the shortcuts page.  Design patterns are at the core of how the Cocoa frameworks interact. Apple provides solid documentation on Cocoa design patterns in the iPhone OS Reference Library and these patterns can be understood at a high-level without delving into any code. This is my suggested approach. If you are not familiar with design patterns, the gang of four book (the GOF book as most often termed in the software world) - Design Patterns: Elements of Reusable Object-Oriented Software, by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, is the official source for design patterns. The theory behind Cocoa's design patterns can be found in this book and for that matter, the use of design patterns in any modern object-oriented software system can be found in this book. The GOF book describes design patterns in a language independent manner. Familiarizing yourself with Cocoa's design patterns from a language independent perspective is a key starting point for building an iPhone application.

Continuing on the topic of cocoa design patterns, Apple's frameworks are designed for re-use. There are folks out there who are very experienced with design patterns and are able to layer design patterns on top of the cocoa frameworks. These individuals understand all of the memory implications. They understand MVC backward and forward and they understand the Cocoa design patterns backward and forward. If you do not fall into this category, then keep it simple. If there is one problem that I have seen across forums and code samples on the Internet, it is that of "fighting the apis". It is very important to not fight the apis. The apple documentation describes the proper use of the iPhone OS frameworks and associated API's. The Apple developer connection provides plenty of sample code so it is important to read through this code to understand the proper use of the iPhone OS APIs.

From inception to app store approval, we spent 5 months developing iLogMiles. While this may seem longer than the standard "2 month" development lifecycle, I can assure you that iLogMiles uses a wide variety of the iPhone OS frameworks. In the coming weeks, we plan on covering the development process from start to finish. I will be talking about code organization, memory management, xcode features, core data, performance optimization, debugging, iterative development, and any other topics that we see useful.

Apple, the Apple logo, iPhone, iPod touch, and iTunes are trademarks of Apple Inc., registered in the U.S. and other countries. iPad is a trademark of Apple Inc. App Store is a service mark of Apple Inc.

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