OC中从字符串中提取日期组件(年,月,日,时,分,秒)

    //获取当前日历
    NSCalendar *calendar = [NSCalendar  currentCalendar];
    //字符串时间
    NSString  *TimeString =@"2015-02-09 10:20:10";
    //日期的格式
    NSDateFormatter  *formatter = [[NSDateFormatter  alloc] init];
    formatter.dateFormat  =@"yyyy-MM-dd  HH:mm:ss";
  
    NSDate *time = [formatter     dateFromString:TimeString];
    
    // 根据时间获得单个日期组件
     NSInteger  year =   [calendar   component:NSCalendarUnitYear  
fromDate:time];
    
    NSLog(@"%ld",year);
    
    //根据时间获得多个日期组件
    NSInteger  unit = NSCalendarUnitYear  |  NSCalendarUnitMonth |  NSCalendarUnitDay|
 NSCalendarUnitHour |  NSCalendarUnitMinute |  NSCalendarUnitSecond ;
    NSDateComponents   *Components =   [calendar  components:unit    fromDate:time];
   
    NSLog(@"%ld-%ld-%ld  %ld:%ld:%ld",Components.year, Components.month,
Components.day, Components.hour, Components.month , Components.second);