MD5加密

在这里记录一下，留着以后用
NSString分类
.h中

#import <Foundation/Foundation.h>

@interface NSString (MD5)
/**
 *  md5加密的字符串
 *
 *  @param str
 *
 *  @return
 */
+ (NSString *) md5:(NSString *) str;

@end

.m中

#import "NSString+MD5.h"
#import <CommonCrypto/CommonDigest.h>

@implementation NSString (MD5)

+ (NSString *) md5:(NSString *) str
{
    const char *cStr = [str UTF8String];
    unsigned char result[16];
    CC_MD5(cStr, strlen(cStr), result); // This is the md5 call
    return [NSString stringWithFormat:
            @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
            result[0], result[1], result[2], result[3],
            result[4], result[5], result[6], result[7],
            result[8], result[9], result[10], result[11],
            result[12], result[13], result[14], result[15]
            ];
}

@end