Unfortunately, the particles only exist in the window server, which is a completely separate process from your app. (It's called backboardd
as of iOS 6.0.) You can deduce this by pausing your app in the debugger while an emitter is running. Even though your app is stopped, the particles continue spawning and moving on the simulator or the device. So there is no way you can access the individual particles.
If your emitter cell's velocityRange
and emissionRange
are both zero (meaning no randomness in the velocity vector of your particles), then you should be able to make the particles decelerate by playing with the xAcceleration
, yAcceleration
, and zAcceleration
properties of the cell. However, the particles will slow to a stop and then reverse direction. If you want the particles to disappear when the stop, set the lifetime
property appropriately.