IOS Objective-C 版本 MD5加密

demo.m

import <CommonCrypto/CommonDigest.h> // md5需要引用这个文件  

// md5 32位 加密  
+ (NSString *) MD5:(NSString *) string {  
    const charchar *cStr = [string UTF8String];  
    unsigned char result[16];  
    CC_MD5(cStr, strlen(cStr), result); // This is the md5 call  
      
    //%02x     格式控制: 以十六进制输出,2为指定的输出字段的宽度.如果位数小于2,则左端补0
    NSString *output = [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]  
            ];  
      
    NSLog(@"MD5 %@", output);  
    return output;  
}

// 优化下，变成这样  
+ (NSString *) MD5:(NSString *) string {  
    const charchar *cStr = [string UTF8String];  
    unsigned char digest[16];  
    CC_MD5( cStr, strlen(cStr), digest ); // This is the md5 call  
      
    NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];  
      
    for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++)  
        [output appendFormat:@"%02x", digest[i]];  
      
    NSLog(@"MD5 %@", output);  
    return output;  
}