Called by the picker view when the user selects a row in a component.
- iOS 2.0+
An object representing the picker view requesting the data.
A zero-indexed number identifying a row of
component. Rows are numbered top-to-bottom.
A zero-indexed number identifying a component of
picker. Components are numbered left-to-right.
To determine what value the user selected, the delegate uses the
row index to access the value at the corresponding position in the array used to construct the component.