NSString进行MD5加密

这种事，弄一个NSString的分类来实现最好

@implementation NSString (MD5)

- (NSString *)MD5String {
    const char *cStr = [self UTF8String];
    unsigned char result[CC_MD5_DIGEST_LENGTH] = {0};
    CC_MD5(cStr, (CC_LONG)strlen(cStr), result);
    
    NSMutableString *ret = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH*2];
    for (int i=0; i<CC_MD5_DIGEST_LENGTH; i++) {
        [ret appendFormat:@"%02X", result[i]];
    }
    return ret;
}

@end

使用很简单

NSString *MD5 = [@"123456" MD5String];