[置顶] iOS关于时间、时间戳操作

#pragma mark -获取字符串形式的时间戳
-(NSString *)getTimeStampString
{
    //获取时间和时间戳
    NSDate* timeStamp = [NSDatedateWithTimeIntervalSinceNow:0];
    NSTimeInterval temp=[timeStamptimeIntervalSince1970]*1000;
    return [NSStringstringWithFormat:@"%.0f", temp];
}

#pragma mark - 时间戳转为NSString
/**
 *  @author zm
 *
 *  @brief  时间戳转为NSString
 *
 *  @param timeStamp   字符串格式的时间戳
 *  @param formatString format格式(默认yyyy-MM-dd HH:mm:ss.SSS)
 *
 *  @return 返回字符串
 */
-(NSString *)event_stringFromTimeStamp:(NSString *)timeStamp formatString:(NSString *)formatString
{
    NSDate *updatetimestamp = [selff_getDateByString:timeStamp];
    NSString *dateFormat =@"yyyy-MM-dd HH:mm:ss.SSS";
    if (formatString) {
        dateFormat = formatString;
    }
    NSDateFormatter *formatter = [[NSDateFormatteralloc]init];
    [formatter setDateStyle:NSDateFormatterMediumStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:dateFormat];
    NSString *dateString = [formatterstringFromDate:updatetimestamp];
    return dateString;
}

#pragma mark -获取字符串形式的当前时间(默认yyyy-MM-dd HH:mm:ss)
+(NSString *)getDateTimeString:(NSDateFormatter *)dateFormatter
{
    if (dateFormatter ==nil) {
        dateFormatter = [[NSDateFormatteralloc]init];
        [dateFormattersetDateFormat:@"yyyy-MM-dd HH:mm:ss.SSS"];
    }
    NSDate *dateNow = [NSDatedate];
    return [dateFormatterstringFromDate:dateNow];
}

#pragma mark -将字符串形式的时间转换为时间戳
+(UInt64)getTimeStampByDateString:(NSString *)dateString
{
    NSDateFormatter *XNNDateFormatter = [[NSDateFormatteralloc]init];
    [XNNDateFormattersetDateFormat:@"yyyy-MM-dd HH:mm:ss.SSS"];
    NSDate *XNNDate= [XNNDateFormatterdateFromString:dateString];
    if(XNNDate){
        return [XNNDatetimeIntervalSince1970]*1000;
    }else{
        return -99999;
    }
}

#pragma mark -字符串转为日期
- (NSDate *)stringToDate:(NSString *)strdate
{
    NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *retdate = [dateFormatter dateFromString:strdate];
    [dateFormatter release];
    return retdate;
}

#pragma mark -日期转为字符串
- (NSString *)dateToString:(NSDate *)date
{
    NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSString *strDate = [dateFormatter stringFromDate:date];
    [dateFormatter release];
    return strDate;
}

#pragma mark -将UTC日期字符串转为本地时间字符串  
//输入的UTC日期格式2013-08-03T04:53:51+0000  
-(NSString *)getLocalDateFormateUTCDate:(NSString *)utcDate  
{  
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];  
    //输入格式  
    [dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZ"];  
    NSTimeZone *localTimeZone = [NSTimeZone localTimeZone];  
    [dateFormatter setTimeZone:localTimeZone];  
      
    NSDate *dateFormatted = [dateFormatter dateFromString:utcDate];  
    //输出格式  
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];  
    NSString *dateString = [dateFormatter stringFromDate:dateFormatted];  
    [dateFormatter release];  
    return dateString;  
}

#pragma mark -将本地日期字符串转为UTC日期字符串  
//本地日期格式:2013-08-03 12:53:51  
//可自行指定输入输出格式  
-(NSString *)getUTCFormateLocalDate:(NSString *)localDate  
{  
   NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
    //输入格式  
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];        
    NSDate *dateFormatted = [dateFormatter dateFromString:localDate];  
    NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:@"UTC"];  
    [dateFormatter setTimeZone:timeZone]; 
   //输出格式 
    [dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZ"];  
    NSString *dateString = [dateFormatter stringFromDate:dateFormatted]; 
    [dateFormatter release]; 
    return dateString;  
} 

- (NSString *)getUTCFormatDate:(NSDate *)localDate
{
    NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
    NSTimeZone *timeZone = [NSTimeZonetimeZoneWithName:@"UTC"];
    [dateFormatter setTimeZone:timeZone];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
    NSString *dateString = [dateFormatter stringFromDate:localDate];
    [dateFormatter release];
    return dateString;
}

- (NSDate *)getLocalFromUTC:(NSString *)utc
{
    NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
    NSTimeZone *timeZone = [NSTimeZonelocalTimeZone];
    [dateFormatter setTimeZone:timeZone];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
    NSDate *ldate = [dateFormatter dateFromString:utc];
    [dateFormatter release];
    return ldate;
}

#pragma mark -世界标准时间UTC /GMT 转为当前系统时区对应的时间 
- (NSDate *)getNowDateFromatAnDate:(NSDate *)anyDate  
{  
    //设置源日期时区  
    NSTimeZone* sourceTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];//或GMT  
    //设置转换后的目标日期时区  
    NSTimeZone* destinationTimeZone = [NSTimeZone localTimeZone];  
    //得到源日期与世界标准时间的偏移量  
    NSInteger sourceGMTOffset = [sourceTimeZone secondsFromGMTForDate:anyDate];  
    //目标日期与本地时区的偏移量  
   NSInteger destinationGMTOffset = [destinationTimeZone secondsFromGMTForDate:anyDate];  
    //得到时间偏移量的差值  
    NSTimeInterval interval = destinationGMTOffset - sourceGMTOffset;  
   //转为现在时间  
   NSDate* destinationDateNow = [[[NSDate alloc] initWithTimeInterval:interval sinceDate:anyDate] autorelease];  
    return destinationDateNow;  
}  
    如：
     //2013-08-03T12:53:51+0800     UTC时间格式下的北京时间，可以看到北京时间＝ UTC + 8小时。
    NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZ"];
    NSDate *localDate = [dateFormatter dateFromString:@"2013-08-03T04:56:52+0000"];      ＋0000 表示的是当前时间是个世界时间。
    [dateFormatter release];
    NSLog(@"now Time = %@",[selfgetNowDateFromatAnDate:localDate]);
结果：
2013-08-03 12:57:33.391 xxxx[2547:c07] now Time = 2013-08-03 12:56:52 +0000
 以上注意一点，在转出来后带的时间是原参数anydate的时区，因此切不可再用NSDateFormatter 转换。否则会多增加一个时区的时间值。应该使用如下来提取字符串
    NSString *str = [NSStringstringWithFormat:@"%@",[selfgetNowDateFromatAnDate:localDate]];
    NSLog(@"str = %@",str);
注NSDate对象存放的日期始终是UTC的标准时间，可以根据这个时间进行其它时间的转换。因此上面算出来的时间中时区为 +0000，如果此时再转为字符串
#pragma mark -比较时间间隔（天数）
+(NSInteger)compareOneDay:(NSDate *)oneDay withAnotherDay:(NSDate *)anotherDay
{
    NSDateFormatter *dateFormatter=[[NSDateFormatteralloc]init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm"];
    NSTimeInterval time =[oneDaytimeIntervalSinceDate:anotherDay];
    NSInteger days=((NSInteger)time)/(3600*24);
    return days;
}

#pragma mark -比较时间间隔（ms）
+(NSInteger)compareOneTime:(NSDate *)oneTime withAnotherTime:(NSDate *)anotherTime
{
    NSDateFormatter *dateFormatter=[[NSDateFormatteralloc]init];
    [dateFormatter setDateFormat:@"HH:mm:ss"];
    NSTimeInterval time =[oneTimetimeIntervalSinceDate:anotherTime];
    //1s = 1000ms
    NSInteger timeT=((NSInteger)time) *1000;
    return timeT;
}

#pragma mark-获取当前时间的年、月、日、时、分、秒
//获取当前时间
NSDate *now = [NSDate date];
NSLog(@"now date is: %@", now);
NSCalendar *calendar = [NSCalendar currentCalendar];
NSUInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
NSDateComponents *dateComponent = [calendar components:unitFlags fromDate:now]；
int year = [dateComponent year];
int month = [dateComponent month];
int day = [dateComponent day];
int hour = [dateComponent hour];
int minute = [dateComponent minute];
int second = [dateComponent second];
NSLog(@"year is: %d", year);
NSLog(@"month is: %d", month);
NSLog(@"day is: %d", day);
NSLog(@"hour is: %d", hour);
NSLog(@"minute is: %d", minute);
NSLog(@"second is: %d", second);