BSD socket in swift

/// ================= 客户端运行程序 =================
        
        /// 创建 socket 接口
        var sockfd_client:Int32
        /// 用于bind服务端信息的 protofamily AN_INIT 决定ipv4(32位IP地址)和端口号(16位)的组合
        var server_addr:sockaddr_in
        
        
        // 第一步：应对服务器的 socket 参数分别是：协议域(族) socket类型 协议
        sockfd_client = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)
        
        // 第二步：填充服务器socket的信息
        server_addr = sockaddr_in()
        server_addr.sin_family = sa_family_t(AF_INET)
        
//        let _ = "127.0.0.1".data(using: .ascii)?.withUnsafeBytes({
//            (ptr: UnsafePointer<Int8>) in
//            inet_pton(AF_INET, ptr, &server_addr.sin_addr.s_addr)
//        })
        server_addr.sin_addr.s_addr  = inet_addr("127.0.0.1")
        server_addr.sin_port = CFSwapInt16(6969)
        
        // 第三步：连接服务器 自动分配一个端口
        //一种方式通过withUnsafePointer withMemoryRebound
//        let _ = withUnsafePointer(to: &server_addr){
//            ptr in
//            ptr.withMemoryRebound(to: sockaddr.self, capacity: 1) {
//                ptrSockAddr in
//                connect(sockfd_client, UnsafePointer(ptrSockAddr), socklen_t(MemoryLayout<sockaddr>.size))
//            }
//        }
        
        //一种方式通过memcpy
        var sock_addr = Darwin.sockaddr(sa_len: 0, sa_family: 0, sa_data: (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0))
        memcpy(&sock_addr, &server_addr, Int(MemoryLayout.size(ofValue: server_addr)))
        
        connect(sockfd_client, &sock_addr, socklen_t(MemoryLayout<sockaddr>.size))
        
        var message = "12345678"
        
        let _ = message.data(using: .ascii)?.withUnsafeBytes({ (ptr:UnsafePointer<Int8>)in
            // 第四步： 向服务器发送一条信息
            send(sockfd_client, ptr, message.characters.count, 0)
        })
        
        
        close(sockfd_client)