But the picture varies according to regions.
IDC said that many markets will show “robust growth” this year and beyond and predicts that worldwide shipments will reach 1.9 billion units by 2019.
China’s smartphone growth will only be 2.5 percent in 2015 and Android growth will also slow there this year and over the next four years.
There are still opportunities for Apple sales because much of the company’s installed base are using old models. Apple wants Android users to switch to iOS but the price difference is holding up its plans.
Here are IDC’s projections for the different operating systems between now and 2019.