According to June data from Nielsen, Apple is the top smartphone manufacturer in the United States, but iOS remains behind Android as a whole for the title of most popular smartphone OS in the country. Apple holds a 28 percent share of the handset market, followed by RIM and HTC, each of which account for 20 percent of the market. When looking at operating systems, iOS again accounts for a 28 percent share of the market, while Android represents 39…