swift md5

swift3 对类型检查严格了

    /// 返回md5 32位小写
    var MD5:String {
        let cString = self.cString(using: String.Encoding.utf8)
        let length = CUnsignedInt(
            self.lengthOfBytes(using: String.Encoding.utf8)
        )
        //let result = UnsafeMutablePointer<CUnsignedChar>(allocatingCapacity: Int(CC_MD5_DIGEST_LENGTH))
        let result:UnsafeMutablePointer<CUnsignedChar> = UnsafeMutablePointer.allocate(capacity: (Int(CC_MD5_DIGEST_LENGTH)))
        CC_MD5(cString!,length,result)
        return String(format:"%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])
        
    }

/**
 *  加密系统头
 */
#import <CommonCrypto/CommonDigest.h>  桥接头文件加入
extension String{
    /// 返回md5 32位小写
    var MD5:String {
        let cString = self.cStringUsingEncoding(NSUTF8StringEncoding)
        let length = CUnsignedInt(
            self.lengthOfBytesUsingEncoding(NSUTF8StringEncoding)
        )
        let result = UnsafeMutablePointer<CUnsignedChar>.alloc(Int(CC_MD5_DIGEST_LENGTH))
        CC_MD5(cString!,length,result)
        return String(format:"%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])
    }
}

oc 版本 头文件 <CommonCrypto/CommonDigest.h>

/// md5 小写
- (NSString *)MD5{
    const char *cStr = [self UTF8String];
    
    unsigned char result[16];
    
    CC_MD5(cStr, (unsigned)strlen(cStr), result);
    
    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]];
}

此方法得到的MD5值中的字母为小写，如果想要大写的MD5值，将@"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x" 中的x替换成X即可