With both Apple (Nasdaq: AAPL) and Google (Nasdaq: GOOG) preparing to host their respective annual developer conferences this month, it's a pretty good a time to talk about developers. Apple's Worldwide Developers Conference, or WWDC, kicks off next week, while Big G's Google I/O takes place later this month, both at the Moscone Center in downtown San Francisco.

Each platform depends critically on its ability to attract talented developers to provide engaging content that keep users coming back for more. Developer loyalty drives consumer loyalty, so it all starts with creating quality apps. Microsoft (Nasdaq: MSFT) has been taking notes as Android flails in the tablet market, which is why it's aggressively courting tablet developers for the impending launch of its tablet-bound Windows 8.

Survey says
According to a recent report from Flurry Analytics, iOS is still the preferred mobile OS among developers. The researcher tracks when companies start new projects on platform-specific software development kits, or SDKs, and here are how its results have come out over the past five quarters.

Newprojectstarts

Source: Flurry Analytics.

Apple continues to maintain its lead in developer interest, with 69% of new project starts focusing on iOS while 31% target Android.

Stop me if you've heard this one before
There are several key drivers to this discrepancy. The first is a theme that continues to pop up time and time again: fragmentation. Android's open nature inevitably leads to a slew of different hardware configurations and software versions that a developer has to target, which dramatically increases the costs of supporting so many devices.

Interestingly, chances are that iOS may add a layer of fragmentation to the iPhone platform this year with the all-but-confirmed 4-inch display that's expected on the sixth-generation iPhone. Rumor has it that Apple is keeping the same width while making the device taller. It may notably increase the pixel resolution to 1136 x 640, compared with the current 960 x 640.

This is important because it changes the aspect ratio from 3:2 to approximately 16:9, so existing apps can't simply scale up or down as they could when Apple merely doubled dimensions for the Retina Display. Most widescreen HD content is formatted in 16:9, so Apple may be looking to better accommodate HD videos.

My neighbor happens to work for an iOS developer, and here's how he put it. Developing for thousands of Android devices wouldn't be so bad if that was a fixed target, but it's not. OEMs are so prolific that more gadgets are hitting the market every month. One new layer of iOS fragmentation every few years is much easier to cope with than dozens each year.

Here's Flurry's visualization of the top 20 selling Android devices.

Androiddevice

Source: Flurry Analytics.

A picture is worth a thousand words, indeed.

Dollars and sense
For whatever reason, iOS users also have a higher propensity to pay for apps. Flurry notes that iOS apps generate four times as much revenue per active user on average relative to Android counterparts. Specifically, Android brings in about 24% as much as iOS for developers.

On top of that, Apple's continued iPad dominance means that iOS developers get exposure to another growing installed base of users in what Flurry calls "the most compelling 'build once, run anywhere' value proposition in the market today."

Simply put, iOS costs less and makes more for developers. Android's deep fragmentation adds considerable expense to developing and supporting the platform, while its users tend to be less willing to pay up for the finished product.

It should be a jam-packed month for mobile watchers and developers alike. Just don't expect Apple CEO Tim Cook or Google CEO Larry Page to get on stage and start a "developers, developers, developers" chant while sweating profusely.

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