UIPickerView, detect “rolling wheel” start and stop?

Question

I just discovered that if I do the following:

1. Click the button that animates a UIPickerView into my view
2. Quickly start the wheel rolling

Answer 1

Since animationKeys seems to not work anymore, I have another solution. If you check the subviews of UIPickerView, you'll see that there is a UIPickerTableView for each component.

This UIPickerTableView is indeed a subclass of UITableView and of course of UIScrollView. Therefore, you can check its contentOffset value to detect a difference.

Besides, its scrollViewDelegate is nil by default, so I assume you can safely set an object of yours to detect scrollViewWillBeginDragging, scrollViewDidEndDecelerating, etc.

By keeping a reference to each UIPickerTableView, you should be able to implement an efficient isWheelRolling method.