Start a node.js server using NSTask in Swift.

main

        let mainBundle = NSBundle.mainBundle()
        let pathToNode = mainBundle.pathForResource("node", ofType: "")! as String
        let pathToNodeApp = mainBundle.pathForResource("server", ofType: "js", inDirectory: "Server")! as String
        let pathToAppFolder = (pathToNodeApp as NSString).stringByDeletingLastPathComponent
        
        task = NodeTask(nodeJSPath: pathToNode, appPath: pathToNodeApp, currentDirectoryPath: pathToAppFolder)
        task.launch()

NodeTask.swift

import Foundation
import Cocoa

class NodeTask: NSObject {
    
    private let processIdentifier = NSProcessInfo.processInfo().processIdentifier
    private let nodeTask = NSTask()
    private let readPipe = NSPipe()
    private let errorPipe = NSPipe()
    private let queue = dispatch_queue_create("NodeTask.output.queue", DISPATCH_QUEUE_SERIAL)
    private var running = false
    
    init(nodeJSPath: String, appPath: String, currentDirectoryPath: String) {
        
        super.init()
        
        readPipe.fileHandleForReading.readabilityHandler = { [unowned self] (handler: NSFileHandle!) in
            dispatch_async(self.queue) {
                if self.running {
                    let data = handler.readDataToEndOfFile()
                    self.onRead(data)
                }
            }
        }
        
        errorPipe.fileHandleForReading.readabilityHandler = { [unowned self] (handler: NSFileHandle!) in
            dispatch_async(self.queue) {
                if self.running {
                    let data = handler.readDataToEndOfFile()
                    self.onError(data)
                }
            }
        }
        
        nodeTask.currentDirectoryPath = currentDirectoryPath
        nodeTask.launchPath = nodeJSPath
        nodeTask.arguments = [appPath, "\(processIdentifier)"]
        nodeTask.qualityOfService = .UserInitiated
        nodeTask.standardOutput = readPipe
        nodeTask.standardError = errorPipe
    }
    
    deinit {
        self.quit()
    }
    
    func launch() {
        
        if !running {
            
            print("------------------------------ Node launch ------------------------------")
            
            running = true
            nodeTask.launch()
        }
    }
    
    func quit() {
        
        dispatch_sync(self.queue) {
            self.terminate()
        }
    }
    
    private func terminate() {
        
        if running {
            
            print("------------------------------ Node quit ------------------------------")
            
            running = false
            readPipe.fileHandleForReading.closeFile()
            errorPipe.fileHandleForReading.closeFile()
            nodeTask.terminate()
        }
        
    }
    
    private func stringFromData(data: NSData) -> String {
        return NSString(data: data, encoding: NSUTF8StringEncoding)!.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()) as String
    }
    
    private func onRead(data: NSData) {
        
        let text = stringFromData(data)
        if text != "" {
            print("Node: \(text)")
        }
    }
    
    private func onError(data: NSData) {
        
        let text = stringFromData(data)
        if text != "" {
            print("------------------------------ Node fatal error ------------------------------")
            print(text)
            self.terminate()
        }
    }
    
}

Hi, I'm trying to start a node server from a swift mac app and came across your example here. It seems that Bundle.main.path(forResource: "node", ofType: "") is null though, is there anythng special I have to do to make node available in my app?

‪Thanks for asking! I bundled the node executable in the app by copying it and adding it to the app target in xcode. Did the same with the js code. ‬

@hfossli, thank you so much for this! I'm trying to adapt it to run a Next.js project that's inside of my Xcode project at ./web. I'm trying to run yarn dev in applicationDidFinishLaunching. I'd love any tips you might have on how to do that given this code, if you have a moment. It's a brand new, Next.js project without any additional configuration. I usually just cd into its root and run yarn dev to start a local server.

I would suggest you bundle it all to one file (main.jsbundle) and try to run that.

What's your goal? Embedding next js in app and render it in a webview? In that case you don't need this. Then a simple main.jsbundle and index.html is all you need for the webview.

Is there a way to do this in objective-c instead of swift

I'm pretty sure you can do convert it line by line to objc

I'm pretty sure you can do convert it line by line to objc

Would you be willing to convert this.
I have no experience with swift or objective-c. I'm currently learning

No