Callback is not invoked when a closure callback-style call is executed in XPC

I noticed a problem while writing a program using XPC on macOS.

When I write it in the form of a closure that receives the result of an XPC call, I can't receive it forever.

I add an XPC target in Xcode, the sample code is used in the pass closure format, but can't I use closure passing with XPC?

My Environment:

• Xcode 15.3
• macOS 14.4.1

caller (closure version)

struct ContentView: View {
  @State var callbackResult: String = "Waiting…"
  var body: some View {
    Form {
      Section("Run XPC Call with no argument and no return value using callback") {
        Button("Run…") {
          callbackResult = "Running…"
          let service = NSXPCConnection(serviceName: "net.mtgto.example-nsxpc-throws-error.ExampleXpc")
          service.remoteObjectInterface = NSXPCInterface(with: ExampleXpcProtocol.self)
          service.activate()
          guard let proxy = service.remoteObjectProxy as? any ExampleXpcProtocol else { return }
          defer {
            service.invalidate()
          }
          proxy.performCallback {
            callbackResult = "Done"
          }
        }
        Text(callbackResult)
        ...
     }
  }
}

callee (closure version)

@objc protocol ExampleXpcProtocol {
    func performCallback(with reply: @escaping () -> Void)
}

class ExampleXpc: NSObject, ExampleXpcProtocol {
    @objc func performCallback(with reply: @escaping () -> Void) {
        reply()
    }
}

I found this problem can be solved by receiving asynchronous using Swift Concurrency.

caller (async version)

struct ContentView: View {
  @State var callbackResult: String = "Waiting…"
  var body: some View {
    Form {
      Section("Run XPC Call with no argument and no return value using callback") {
        Button("Run…") {
          simpleAsyncResult = "Running…"
          Task {
            let service = NSXPCConnection(serviceName: "net.mtgto.example-nsxpc-throws-error.ExampleXpc")
            service.remoteObjectInterface = NSXPCInterface(with: ExampleXpcProtocol.self)
            service.activate()
            guard let proxy = service.remoteObjectProxy as? any ExampleXpcProtocol else { return }
            defer {
              service.invalidate()
            }
            await proxy.performNothingAsync()
            simpleAsyncResult = "DONE"
          }
          Text(simpleAsyncResult)
        ...
     }
  }
}

callee (async version)

@objc protocol ExampleXpcProtocol {
    func performNothingAsync() async
}

class ExampleXpc: NSObject, ExampleXpcProtocol {
    @objc func performNothingAsync() async {}
}

To simplify matters, I write source code that omits the arguments and return value, but it is not also invoked by using callback style.

All sample codes are available in https://github.com/mtgto/example-nsxpc-throws-error