Create a socket in Swift

Question

I'm trying to write a simple echo server with swift. The examples I found are either non-functional and low-level or written in objective-c.

I failed at a lot of things, I will start from the top. I cannot manage to create a simple socket using higher-level functions like CFSocketCreate. This is what I ended up with:

class EchoServer : NSObject, NSStreamDelegate
{
    private var serverSocket: CFSocketRef?

    func start()
    {
        self.serverSocket = CFSocketCreate(kCFAllocatorDefault, AF_INET, SOCK_STREAM, 0, 2, &self.acceptConnection, NSNull())
    }

    func acceptConnection(socket: CFSocketRef, type: CFSocketCallBackType, address: CFDataRef, data: UnsafePointer<Void>, info: UnsafeMutablePointer<Void>)
    {
        // Accept connection and stuff later
    }
}

I am new to xcode/objectivec/swift and I'm having a hard time even understanding the error message. The above code leaves me simply with

EchoServer.swift:31:93: '(CFSocketRef, type: CFSocketCallBackType, address: CFDataRef, data: UnsafePointer, info: UnsafeMutablePointer) -> ()' is not convertible to '@lvalue inout $T10'

I'm not even able to make head or tail of this.

any luck with creating your custom server in Swift? I am working on it too, and stuck on the first line in EchoServer :) — János
Sorry no. Swift kept being so unbearably buggy that I entirely switched to nw.js for my project. — Lukas

outcoldman outcoldman · Accepted Answer · 2016-05-22T20:55:12

If somebody is still looking for the answer on this question. I modified code a little. There were some typing issues in the callback, plus it could not be a function on the class.

import CoreFoundation

func acceptConnection(socket: CFSocket!, type: CFSocketCallBackType, address: CFData!, data: UnsafePointer<Void>, info: UnsafeMutablePointer<Void>)
{
    // Accept connection and stuff later
}

class EchoServer : NSObject, NSStreamDelegate
{
    private var serverSocket: CFSocketRef?

    func start()
    {
        self.serverSocket = CFSocketCreate(kCFAllocatorDefault, AF_INET, SOCK_STREAM, 0, 2, acceptConnection, nil)
    }
}

Create a socket in Swift

2 Answers