Either it's your first phone, then you're not counted as switch
Is a switch from a "feature phone" to a smartphone counted as a switch or a first time?
Obviously for marketing purposes, they wouldn't consider that a switch.
But with it being a 2 player market and Android having the lions share, it's obvious that most switchers to iphone will have come from Android. The same would be true for switchers to Android. The question is, are the people switching to Iphone greater than the numbers switching to Android.
Also recent numbers will be skewed by the introduction of the Iphone to several countries, most notably China. In established markets, for several years the Iphone user base has been stagnant or dropping slightly with 75-80% of Iphone purchases being from current Iphone users.