Run a system before the bevy application exits

[Akaam-Zain]

I have client-server bevy application which communicates through a TCP connection. When the client window is closed by the client - before the application actually exits I want to send a message to the server indication that the client is terminated. For that I need to know how I could add a system just before the bevy application exits.

Appreciate your help. Thanks!

[tim-blackbird]

You can listen for an AppExit event in a system in the PostUpdate stage.

[Akaam-Zain]

Hey, appreciate your answer. But would be grateful if you could elaborate on how it could be done. I am quite new to Bevy.
Here's my current implementation

fn exit_system(mut connection: ResMut<Connection>) {

    let events = Events::<AppExit>::default();
    let mut reader = events.get_reader();

    if reader.iter(&events).count() > 0 {
        //... my implmentation
    }

And I call the above system as:
.add_system_to_stage(CoreStage::PostUpdate, exit_system)

[NiklasEi]

You should get the EventReader as a parameter of your system.
See for example

bevy/examples/app/drag_and_drop.rs

Line 12 in a1d3f1b

fn file_drag_and_drop_system(mut events: EventReader<FileDragAndDrop>) {

[Akaam-Zain]

@NiklasEi and @devil-ira thank you - much appreciated. That solved the problem.