According to Financial Times, Apple is at risk of losing one of its key competitive advantages over the rival Android system as application developers say they are warming to Google's smartphone platform.
The app store on Google smartphones, where users can download new games and software, was a key area where Android smartphones have long lagged behind the iPhone.
However the sheer scale of Android, which now accounts for three out of every four smartphones sold, is commanding developers' attention, despite their continuing difficulties in making as much money on Android as on Apple's App Store, which holds credit card details for more than 400m people.
"Android is the platform of growth," says Misha Lyalin, chief executive of Zeptolab, creator of the popular Cut the Rope mobile games. The availability of apps is a major consideration when consumers decide which smartphone or tablet to buy, and purchasing a lot of apps on a platform can make them more reluctant to switch platforms when upgrading their device.
However he says developer feeling remains "very mixed" on the relative merits of the two market leaders, with Apple's App Store containing a richer selection of high-quality apps because of the greater ability to sell them rather than merely rely on advertising for income. Engagement among users is "disproportionately higher" on Apple's iOS than Android, he adds.
In November, Apple had about 700,000 available apps, as did Google, though, Apple only allows apps that pass its strict vetting procedure to enter its App Store, an approach intended to ensure quality and security for iPhone users. Google does not review any Android apps before making them available through its marketplace, giving developers more freedom but increasing risks for users.
However, the search company has made greater efforts to curate its app store and help users to find the best software, as well as selling movies, books and music, with the launch of Google Play in March.
Although the war for mobile talent remains fierce, the falling costs and wider skills needed to create apps mean that it is more feasible to develop for multiple platforms.
In September, Google announced that 25bn apps had been downloaded to Android devices since the platform launched, a milestone Apple reached the previous March and had topped by October, when it surpassed 35bn.
Loren Brichter, a former graphics engineer at Apple and now developer of Letterpress, a word game that was runner-up in Apple's "Best of 2012" app awards, says he is "constantly re-evaluating" the two rival platforms. "I am obviously biased towards Apple but Google is catching up," he says.
Fragmentation of different operating system versions and devices running Android means developing for the platform is "a complete mess", Mr Brichter says, but "there are so many Android users out there, it's increasingly hard to ignore".