Apple is increasing world-wide, where they recently grabbed over 20%, moving ahead of Samsung!
And in the USA, Apple is over 40%, being the Number one Smartphone manufacturer, and well ahead of Samsung by a large margin! ... :-) ...
Apple's smartphone market share is expected to decline over the next three years.
It's interesting to note that while Apple only enjoyed 13.6% of the world's share of UNITS in 2014, they had 30.4% of sales dollars in 2014. In other words, they charge a lot more for their stuff... despite having similar or even less functionality.
Apple spends a lot in marketing, so their stuff costs a lot to make up for those costs. That's all fine... their choice.
http://www.idc.com/getdoc.jsp?containerId=prUS25282214