XCode+Swift+XPC: How to start and deploy a Swift XPC target on MacOS

DISCLAIMER: I am relatively new to MacOS/XCode

I want to build a simple XPC Launch Agent in Swift (ie: in

~/Library/LaunchAgents

~/Library/LaunchAgents/com.demo.myservice.plist

Versions:
- MaOS: 10.13.2
- Xcode: 9.2

Instruction to create the XCode XPC Project with XCode:

1. File > New project
2. I chose the MacOS template: XPC
3. I create the bundle ‘com.demo.myservice’
4. It creates me an Objective-C project. So I delete all files (ie:

   myserviceProtocol.h

   ,

   myservice.h

   ,

   myservice.m

   ,

   main.m

   and

   Info.plist

5. Create the files:

myserviceProtocol.swift

import Foundation

@objc(myserviceProtocol) protocol myserviceProtocol {

  func ping()

}

myservice.swift

import Foundation

class myservice : NSObject, myserviceProtocol {

  func ping() {

    print("ping")

  }

}

main.swift

import Foundation

class ServiceDelegate : NSObject, NSXPCListenerDelegate {

  func listener(_ listener: NSXPCListener, shouldAcceptNewConnection newConnection: NSXPCConnection) -> Bool {

    newConnection.exportedInterface = NSXPCInterface(with:myserviceProtocol.self)

    let exportedObject = myservice()

    newConnection.exportedObject = exportedObject

    newConnection.resume()

    return true

  }

}

let delegate = ServiceDelegate()

let listener = NSXPCListener.service()

listener.delegate = delegate; listener.resume()

Info.plist

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">

  <dict>

    <key>KeepAlive</key>

      <true/>

    <key>Label</key>

      <string>com.demo.myservice</string>

    <key>ProgramArguments</key>

    <array>

       <string>myservice</string>

    </array>

    <key>RunAtLoad</key>

      <true/>

  </dict>

</plist>

1. I build it. No problem
2. I copied

   Info.plist

   into ~/Library/LaunchAgents/ :

cp ~/Documents/myservice/myservice/Info.plist ~/Library/LaunchAgents/com.demo.myservice.plist

I retrieve my userid with

id -u (it returns 501)

And then I try to execute it from the command line (as it does not seem to do anything from Xcode):

sudo launchctl debug user/501/com.demo.myservice /Users/olivier/Library/Developer/Xcode/DerivedData/myservice-hbwefcgibyqbajguvblgcmxsnrmd/Build/Products/Debug/myservice.xpc

Configuration failed: 113: Could not find specified service

Could not find service "com.demo.myservice" in domain for uid: 501

I am not really sure of what I am doing. Was I right to use

XPC