iOS MD5大写32位/16位加密

#pragma mark - MD5加密 16位 大写
+ (NSString *)MD5ForUpper16Bate:(NSString *)str{
    
    NSString *md5Str = [self MD5ForUpper32Bate:str];
    
    NSString *string;
    for (int i=0; i<24; i++) {
        string=[md5Str substringWithRange:NSMakeRange(8, 16)];
    }
    return string;
}
#pragma mark - MD5加密 32位 大写
+ (NSString *)MD5ForUpper32Bate:(NSString *)str{
    
    //要进行UTF8的转码
    const char* input = [str UTF8String];
    unsigned char result[CC_MD5_DIGEST_LENGTH];
    CC_MD5(input, (CC_LONG)strlen(input), result);
    
    NSMutableString *digest = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for (NSInteger i = 0; i < CC_MD5_DIGEST_LENGTH; i++) {
        [digest appendFormat:@"%02X", result[i]];
    }
    
    return digest;
}