Limiting UIDatePicker dates from a particular time. Such as Input DOB to a restricted age limit

You can use dateByAddingUnit and subtract 16 years from current date to set the maximum date for your datePicker as follow:

datePicker.maximumDate = NSCalendar.currentCalendar().dateByAddingUnit(.Year, value: -16, toDate: NSDate(), options: [])

Xcode 10.2.1 • Swift 5

datePicker.maximumDate = Calendar.current.date(byAdding: .year, value: -16, to: Date())