以毫秒为整数值的时间戳转换

• 时间戳转化为时间NSDate

- (NSString *)timeWithTimeIntervalString:(NSString *)timeString{    // 格式化时间    NSDateFormatter* formatter = [[NSDateFormatter alloc] init];    formatter.timeZone = [NSTimeZone timeZoneWithName:@"shanghai"];    [formatter setDateStyle:NSDateFormatterMediumStyle];    [formatter setTimeStyle:NSDateFormatterShortStyle];    [formatter setDateFormat:@"yyyy年MM月dd日 HH:mm"];        // 毫秒值转化为秒    NSDate* date = [NSDate dateWithTimeIntervalSince1970:[timeString doubleValue]/ 1000.0];    NSString* dateString = [formatter stringFromDate:date];    return dateString;}

• 时间转化为时间戳

// 当前时间     NSDate* date = [NSDate dateWithTimeIntervalSinceNow:0];    NSTimeInterval a=[date timeIntervalSince1970]*1000; // *1000 是精确到毫秒，不乘就是精确到秒    NSString *timeString = [NSString stringWithFormat:@"%.0f", a]; //转为字符型

• 通过比较时间与当前时间返回年月日的方法

- (void)getBabyDetailAge:(NSString *)date{    // 获得日期对象    NSDateFormatter *formatter_ = [[NSDateFormatter alloc] init];    formatter_.dateFormat = @"yyyy-MM-dd HH:mm:ss";    NSDate *createDate = [formatter_ dateFromString:date];        NSCalendar *gregorian = [[ NSCalendar alloc ] initWithCalendarIdentifier : NSCalendarIdentifierGregorian];    NSUInteger unitFlags = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear;    NSDateComponents *components = [gregorian components:unitFlags fromDate:createDate toDate:[NSDate date] options: 0 ];        NSInteger years = [components year];    NSInteger months = [components month ];    NSInteger days = [components day ];}