speed
The rate at which the simulation executes.
Declaration
var speed: CGFloat { get set }Discussion
The default value is 1.0, which means that 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 2.0 indicates that time in the physics simulation passes twice as fast as the scene’s simulation time. A value of 0.0 pauses the physics simulation.