The rate at which the simulation executes.
- iOS 7.0+
- macOS 10.9+
- tvOS 9.0+
- watchOS 3.0+
The default value is
1, which means the simulation runs at normal speed. A value other than the default changes the rate at which time passes in the physics simulation. For example, a speed value of
2 indicates that time in the physics simulation passes twice as fast as the scene’s simulation time. A value of
0 pauses the physics simulation.