Date pickers use the Target-Action design pattern to notify your app when the user changes the selected date. To be notified when the date picker’s value changes, register your action method with the valueChanged event. At runtime the date picker calls your methods in response to the user selecting a date or time.
You connect a date
picker to your action method using the addTarget(_:action:for
method
or by creating a connection in Interface Builder. The signature of an
action method takes one of three forms, which are listed in Listing 1.
Choose the form that provides the information that you need to respond
to the value change in the date picker.
Listing 1 Action methods for date pickers
@IBAction func doSomething()
@IBAction func doSomething(sender: UIDatePicker)
@IBAction func doSomething(sender: UIDatePicker, forEvent event: UIEvent)
