Struct Schedule 

pub struct Schedule { /* private fields */ }

An ordered list of systems, run together — one Schedule backs each SystemStage. Deferred Commands (entity spawns, resource inserts/removes, triggers) are flushed after each system, not just once at the end — so a system ordered .after(...) another can rely on seeing its Commands effects, even within the same stage.

Systems normally run in the order they were added. Call .after(...)/ .before(...) directly on a system (see IntoSystemConfig) to constrain it relative to another system known to the schedule — added earlier or later, registration order doesn’t matter, only the constraint does. .priority(...) breaks ties between systems with no after/before relationship to each other — higher runs first — but never overrides an explicit constraint. .chain() on a tuple of systems (see Chain, registered with add_systems) forces them to run in that exact relative order, and can itself be given .after(...)/.before(...)/ .priority(...), applied to the whole chain:

schedule
    .add_system(spawn_enemies)
    .add_system(move_enemies.after(spawn_enemies))
    .add_system(render.after(move_enemies))
    .add_system(hud.priority(10))
    .add_systems((physics_step, resolve_collisions).chain().before(render));

Implementations

impl Schedule

pub fn add_system<S, Params>( &mut self, system: impl Into<SystemConfig<S, Params>>, ) -> &mut Self

where Params: 'static, S: IntoSystem<Params> + 'static,

Appends system to the end of this schedule. system may be a bare system, or one wrapped with .after(...)/.before(...)/.priority(...) — see IntoSystemConfig.

pub fn add_systems(&mut self, chain: SystemChain) -> &mut Self

Appends every system in chain (built with .chain() on a tuple of systems — see Chain) to the end of this schedule.

pub fn run(&mut self, world: &mut World, resources: &mut Resources)

Runs every system in order, flushing deferred entity spawns, resource commands, and triggered observers after each system — not once at the end of the whole schedule. This is what lets a system that reads a resource another system just inserted via Commands::insert_resource see it immediately, as long as it’s ordered .after(...) the system that queued it — the two don’t need to be in different stages.

Trait Implementations

impl Default for Schedule

fn default() -> Schedule

Returns the “default value” for a type.