Developing for the iPhone and Android: The pros and cons

What you need to know before writing apps for either platform -- or for both

Smartphones and their apps are the new way of the world, and developers are lured by their increasing popularity. But with two major platforms -- Apple's recently upgraded and renamed iOS 4 and Google's Android -- competing with one another, how does a developer choose between them?

In fact, how would developers interested in maximum exposure for their apps fare by targeting either -- or both -- platforms? What roadblocks are there, and how does a developer get around them? I'll take a look at these questions and relay advice from experienced developers on both platforms.

Programming languages

For developers who have one app in mind and envision their code running on multiple mobile platforms, the going is rough in today's world.

Android apps are written in the Java programming language. Many developers have made careers in enterprises by becoming very proficient in Java, so developing for the Android platform is a natural fit for those folks.

On the other hand, applications that run natively on the iPhone operating system are written in Apple's Objective-C, a dialect of the more common C language that has elements of Smalltalk. (Technically speaking, Objective-C is a small, strict superset language on top of C, so any C program will compile with an Objective-C compiler, and a developer can include C code within an Objective-C class.) Developers who have spent their careers working with C and C++ probably won't find Objective-C to be a difficult language to pick up, although there may be speed bumps along the way.

"There is no obvious way to write one set of code that targets both platforms," says Matthew Baxter-Reynolds, director of AMX Software Ltd., a software development firm in England, and author of the upcoming book Multimobile Development: Building Applications for Any Smartphone. "You cannot run Java on iPhone, and you cannot run Objective-C on Android."

Writing for multiple platforms

That was the story for a while -- you had to develop your apps in the native language for each device. Over the past year or so, however, new tool kits and development platforms have emerged in the marketplace to make it possible for programmers create iPhone applications without having to study Objective-C.

Tool kits such as Rhomobile's Rhodes, Nitobi's PhoneGap, Appcelerator's Titanium and Ansca's Corona make it relatively simple to create apps that will run on some combination of the iPhone, BlackBerry, Windows Mobile, Symbian and Android platforms.

However, these emulators and runtime layers are new and not full-featured. While simple applications accessing the Web and bringing information back to the phone are appropriate for these types of frameworks, mobile apps relying on intense calculations and heavy database access -- which includes some custom-written line-of-business applications -- are not good candidates, because running a compatibility framework exacts an overhead penalty on a limited-power mobile processor that most users find unacceptable.

In addition, there are currently no good solutions for providing cross-platform support for a graphically intensive application, like a game or a video editor.

In other words, there's still nothing to change the fact that you're working with two different platforms and two different native languages. For now, the solution is to rewrite the application into the desired target platform's native language.

Closed vs. open systems

Android is well liked by some developers because it provides an open development platform, one on which rich applications with potentially game-changing feature sets can be deployed. Developers can leverage the Android device hardware, create location-aware apps by accessing GPS and other sensory information on the device, set alarms to remind users of events, include notifications and other information on the status bar of the device, and more.

In contrast, iPhones have difficulty displaying multiple notifications, since applications are restricted to pop-up messages that are shown only one at a time. Additionally, developers on Android, at least in the United States, can leverage various carrier features across the spectrum of Android devices, whereas iPhone devices are limited to the network features that AT&T allows.

With the functionality of the Android 2.2 software development kit (SDK), a developer can build apps that use either the touch screen or the device keyboard. This is an important point, since Android developers have to accommodate a larger set of devices, all with different hardware configurations.

In a recent TechRepublic article, Justin James reported that Jason Chen, an Android developer advocate at Google, said the two biggest hurdles for first-time Android developers to overcome are understanding and handling the multitasking on the Android platform and dealing gracefully with app interruptions, like receiving an incoming SMS text message or phone call.

On the other hand, developers fare pretty well when writing apps for the iPhone, at least at the outset. Since the iPhone operating system is a closed system, created specifically by Apple for its own devices, developers have a known spectrum of devices to target, with a well-defined scope of capabilities and limitations.

Some developers report that this closed-system model makes for better usability -- a trait for which Apple products have traditionally been lauded. With such tight integration of the phone, operating system and third-party apps, users' defined expectations are met with a minimum of fuss around getting an app on the phone, what it does when it's on the phone, and what features that app will support.

That's a good thing from the drawing board perspective, but in some instances -- for example, where your software could work better, or at least differently, with a different type of device -- it limits the flexibility developers have in creating apps.

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