iOS NSDate 和NSString RFC1123格式互转

以下内容来自于 MKNetworkKit iOS开源库中文件 ”NSDate＋RFC1123“

NSDate＋RFC1123.h文件

//
//  NSDate+RFC1123.h
//  MKNetworkKit
//
//  Created by Marcus Rohrmoser
//  http://blog.mro.name/2009/08/nsdateformatter-http-header/
//  http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1

//  No obvious license attached

@interface NSDate (RFC1123)
/**
 Convert a RFC1123 'Full-Date' string
 (http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1)
 into NSDate.
 */
+(NSDate*)dateFromRFC1123:(NSString*)value_;

/**
 Convert NSDate into a RFC1123 'Full-Date' string
 (http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1).
 */
-(NSString*)rfc1123String;

@end

NSDate＋RFC1123.m文件

//
//  NSDate+RFC1123.m
//  MKNetworkKit
//
//  Originally created by Marcus Rohrmoser
//  http://blog.mro.name/2009/08/nsdateformatter-http-header/
//  Updated with strptime methods by Bo98
//
//  No obvious license attached

#import "NSDate+RFC1123.h"
#import <time.h>
#import <xlocale.h>

@implementation NSDate (RFC1123)

+(NSDate*)dateFromRFC1123:(NSString*)value_
{
    if(value_ == nil)
        return nil;    

    const char *str = [value_ UTF8String];
    const char *fmt;
    NSDate *retDate;
    char *ret;

    fmt = "%a, %d %b %Y %H:%M:%S %Z";
    struct tm rfc1123timeinfo;
    memset(&rfc1123timeinfo, 0, sizeof(rfc1123timeinfo));
    ret = strptime_l(str, fmt, &rfc1123timeinfo, NULL);
    if (ret) {
        time_t rfc1123time = mktime(&rfc1123timeinfo);
        retDate = [NSDate dateWithTimeIntervalSince1970:rfc1123time];
        if (retDate != nil)
            return retDate;
    }


    fmt = "%A, %d-%b-%y %H:%M:%S %Z";
    struct tm rfc850timeinfo;
    memset(&rfc850timeinfo, 0, sizeof(rfc850timeinfo));
    ret = strptime_l(str, fmt, &rfc850timeinfo, NULL);
    if (ret) {
        time_t rfc850time = mktime(&rfc850timeinfo);
        retDate = [NSDate dateWithTimeIntervalSince1970:rfc850time];
        if (retDate != nil)
            return retDate;
    }

    fmt = "%a %b %e %H:%M:%S %Y";
    struct tm asctimeinfo;
    memset(&asctimeinfo, 0, sizeof(asctimeinfo));
    ret = strptime_l(str, fmt, &asctimeinfo, NULL);
    if (ret) {
        time_t asctime = mktime(&asctimeinfo);
        return [NSDate dateWithTimeIntervalSince1970:asctime];
    }

    return nil;
}

-(NSString*)rfc1123String
{
    time_t date = (time_t)[self timeIntervalSince1970];
    struct tm timeinfo;
    gmtime_r(&date, &timeinfo);
    char buffer[32];
    size_t ret = strftime_l(buffer, sizeof(buffer), "%a, %d %b %Y %H:%M:%S GMT", &timeinfo, NULL);
    if (ret) {
        return @(buffer);
    } else {
        return nil;
    }
}

@end

测试：

    NSDate* now = [NSDatedate];

   NSLog(@"now = %@",now);

   NSString* rfcStr = [now rfc1123String];

   NSLog(@"rfcStr = %@",rfcStr);

    

   NSDate* dateFormRfc = [NSDatedateFromRFC1123:rfcStr];

   NSLog(@"dateFormRfc = %@",dateFormRfc);

输出结果：

2014-12-29 16:48:15.622 [1914:89248] now = 2014-12-29 08:48:14 +0000

2014-12-29 16:48:20.061 [1914:89248] rfcStr = Mon, 29 Dec 2014 08:48:14 GMT

2014-12-29 16:48:26.303 [1914:89248] dateFormRfc = 2014-12-29 08:48:14 +0000