import Foundation

@objc(myserviceProtocol) protocol myserviceProtocol {
    func ping()
}

import Foundation

class myservice : NSObject, myserviceProtocol {
    func ping() {
        print("ping")
    }
}

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
    }
}

// Create the listener and resume it:
//
let delegate = ServiceDelegate()
let listener = NSXPCListener.service()
listener.delegate = delegate;
listener.resume()

<?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>

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