Runtime Function - iced::daemon

Authoritative source: ref/doc/iced/fn.daemon.html.

# Verified signature

pub fn daemon<State, Message, Theme, Renderer>(
    boot: impl BootFn<State, Message>,
    update: impl UpdateFn<State, Message>,
    view: impl for<'a> ViewFn<'a, State, Message, Theme, Renderer>,
) -> Daemon<impl Program<State = State, Message = Message, Theme = Theme>>
where
    State: 'static,
    Message: Send + 'static,
    Theme: Base,
    Renderer: Renderer,

# Use this when...

• Your app behaves like a background/utility process.
• You need daemon-style lifecycle and often multi-window orchestration.
• You still want typed Iced message flow and UI composition.

# Minimal example

pub fn main() -> iced::Result {
    iced::daemon(App::new, App::update, App::view).run()
}

# How it works

daemon mirrors application but targets daemon-like behavior. You still use boot/update/view, tasks, and subscriptions, but lifecycle choices fit background-centric apps.

# Common patterns

// From multi-window style apps:
// - create window/task on message
// - handle close/exit messages centrally in update
// - keep subscriptions active for window events

# Gotchas / tips

• Use this only when daemon semantics are actually needed; otherwise application is simpler.
• Keep window-creation and shutdown messages explicit in your Message enum.
• Validate exit paths carefully, especially when multiple windows/resources exist.

# Example references

• ref/examples/multi_window/src/main.rs

# Related

• Runtime API
• Runtime Function - exit