I wrote another Seeking Alpha article on Apple, this one addressing the concern that Apple's market share would suffer as a result of competition and that its days as the belle of the ball were numbered. I discuss the deceptively simple formula that:
(profit per unit) x (units sold) = overall profit.
I point out that "market share" isn't an element of this formula, though it definitely gets a lot of press. What may be worth looking at in particular is the article's YCharts graph depicting profit margins over time. Competition hasn't been hurting Apple :-)