Instance Property


The duration, in seconds, over which the system spawns new particles. Animatable.


@property(nonatomic) CGFloat emissionDuration;


The birthRate property determines the number of particles spawned during this duration. You can randomize the duration with the emissionDurationVariation property.

A duration of 0.0 specifies that all particles (the value of the birthRate property) spawn instantaneously. Use this duration to create randomized static effects in your scene. For example, by combining this option with the birthLocation and imageSequenceInitialFrameVariation properties, you can cover a plane with a variety of sprites, creating the appearance of a grassy field.

The default value is 1.0 seconds.

You can animate changes to this property’s value. See Animating SceneKit Content.

See Also

Managing Particle Emission Timing


The range, in seconds, of randomized emission duration values. Animatable.


The duration, in seconds, of periods when the system emits no particles. Animatable.


The range, in seconds, of randomized idle duration values. Animatable.


A Boolean value that determines whether the system repeats its emission and idle periods.


The duration, in seconds, for which particles are spawned before the system is first rendered. Animatable.


The number of particles spawned during each emission period. Animatable.


The range of randomized particle birth rate values. Animatable.