No. WhatsApp's primary markets are India and Brazil. In India, iOS's market share is less than 2%. In Brazil, it's a respectable 12%, but WhatsApp is hugely dominant in contemporary communication in Brazil.

[1] http://www.statista.com/statistics/262157/market-share-held-... [2] http://www.statista.com/statistics/262167/market-share-held-...