Checklist P259 App Crash on trying to set Today's Date

When I click on the “Due Date”, the app will crash。Why?:cold_sweat:

var dueDate = NSDate()

func showDatePicker() {

datePicker.setDate(dueDate, animated: false)
}

fatal error: unexpectedly found nil while unwrapping an Optional value
(lldb)

I know that the problem is, the datePicker’s outlet not connected.