Programming physical property of gravity!

nodeName!.physicsBody?.affectedByGravity = true //there is gravity
nodeName!.physicsBody?.affectedByGravity = false //not gravity

To help the programmer

Using the physical property of gravity, you can specify the object of attraction to the earth. AffectedByGravity – boolean value that indicates whether this physics body is affected by the physics world’s gravity.
The physics world’s gravity property defines the gravitational forces applied to volume-based bodies in the scene. The default value is true. This property is ignored on edge-based bodies, which are already unaffected by gravity.
Physics bodies with affectedByGravity set to false are still affected by the gravity fields created by linearGravityField (withVector) and radialGravityField ().