Apple still has feature fragmentation. Airdrop is going to be Iphone 5 or above only.
That's not relevant to developers though. Airdrop is implemented behind an activity view. Any iOS application using activity views gets Airdrop support included automatically when it is available, and they get their current behaviour when it's unavailable. They don't have to do anything to support both cases, it all just works automatically.
Compare this to an experience we had with building an application for Android recently. The client came back and asked us when we were adding certain form fields. We were puzzled - the developer had told us they were already in there. We looked at it - they were in there, but their selected/deselected state was practically indistinguishable. We talked to the developer - it looked fine to him. These were standard form controls, and they looked different on every device we had, to the point where they were invisible or defective on some. We ended up having to use custom graphics instead.
You really can't compare iOS "fragmentation" with Android fragmentation. They really are two entirely different things.