SpatialEventGesture
A gesture that provides information about ongoing spatial events like clicks and touches.
Declaration
struct SpatialEventGestureOverview
Use a gesture of this type to track multiple simultaneous spatial events and gain access to detailed information about each. For example, you can place a particle emitter at every location in a Canvas that has an ongoing spatial event:
struct ParticlePlayground: View {
@State var model = ParticlesModel()
var body: some View {
Canvas { context, size in
for particle in model.particles {
context.fill(Path(ellipseIn: particle.frame),
with: .color(particle.color))
}
}
.gesture(
SpatialEventGesture()
.onChanged { events in
for event in events {
if event.phase == .active {
// Update particle emitters.
model.emitters[event.id] = ParticlesModel.Emitter(
location: event.location
)
} else {
// Remove emitters when no longer active.
model.emitters[event.id] = nil
}
}
}
.onEnded { events in
for event in events {
// Remove emitters when no longer active.
model.emitters[event.id] = nil
}
}
)
}
}The gesture provides a SpatialEventCollection structure when it detects changes. The collection contains SpatialEventCollection.Event values that represent ongoing spatial events. Each event contains a stable, unique identifier so that you can track how the event changes over time. The event also indicates its current location, a timestamp, the pose of the input device that creates it, and other useful information.
The phase of events in the collection can change to SpatialEventCollection.Event.Phase.ended or SpatialEventCollection.Event.Phase.cancelled while the gesture itself remains active. Individually track state for each event inside onChanged(_:) or updating(_:body:) and clean up all state in onEnded(_:).