Apple's growth was detailed on Friday by InMobi, the largest independent mobile advertising network, which released its "Mobile Insights Report: North American Edition" for the month of January. The data comes from InMobi's network, serving more than 93.4 billion advertising impressions around the world each month.
Apple's share of available ad impressions in North America grew from 23.2 percent in October of 2011 to 35.3 percent in January. The 12.1 percentage point swing came as Android loss 3.2 points, finishing in second with 32.7 percent.
In regaining the top spot, Apple rebounded strongly from 2011, during which Google's Android was the top platform tracked by InMobi for most of the year.
Research in Motion's BlackBerry mobile operating system saw an even steeper decline than Android over the October-to-January span, dropping 8.9 points to finish in third place at 11.6 percent.
"The iOS growth we are seeing may be attributed to the tremendous success of iPhone 4S and iPad in the ecosystem," said Anne Frisbie, vice president and managing director for InMobi's North American operations. "Overall, we are excited to see InMobiâs available impressions exceed 55 billion in North America, and look forward to continuing our rapid growth through 2012."
The latest study also found that the top three handsets tracked on the advertising network were all made by Apple. The most popular device tracked in North America was the iPhone 4, with a 9 percent share of impressions, followed by the first-generation iPad with 6.3 percent and the fourth-generation iPod touch with 6.1 percent.