问空的NSDatePicker

EN

[datePicker setDateValue:nil];

if(date == nil) {

    // Set Specific Date
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyyMMdd"];
    NSDate *nilDate = [dateFormat dateFromString:@"20000101"];  
    [datePicker setDateValue:nilDate];

    // Or Disable
    [datePicker setEnabled:FALSE];

} else {

    // Update Date
    [datePicker setDateValue:date];

}

@IBOutlet weak var datePicker: NSDatePicker!
datePicker.datePickerElements = NSDatePickerElementFlags(rawValue: 0)

class MyDatePicker: NSDatePicker {

    var date: Date? {
        didSet {
            if let date = date {
                self.dateValue = date
                self.datePickerElements = .yearMonthDayDatePickerElementFlag
            } else {
                self.datePickerElements = NSDatePickerElementFlags(rawValue: 0)
            }
        }
    }

    override func becomeFirstResponder() -> Bool {
        if date == nil {
            date = Date()
        }
        return true
    }

    override func resignFirstResponder() -> Bool {
        editing = false
        date = self.dateValue
        return super.resignFirstResponder()
    }
}