- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)onclick:(id)sender {
    NSDate *theDate = self.dataPicker.date;
    
    // descriptionWithLocale 方法返回本地時間
    // currentLocale 返回當前使用者信息
    NSLog(@"the date picked is: %@", [theDate descriptionWithLocale:[NSLocale currentLocale]]);
    
    // 設定格式化格式
    // dd和DD的區別
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
    
    // 輸出
    NSLog(@"the date formate is: %@",[dateFormatter stringFromDate:theDate]);
    self.label.text = [dateFormatter stringFromDate:theDate];
    
}
    

詳見注釋：關於dd和DD的區別就是，dd返回當前月份的第幾天，而DD返回當年的第幾天