Creating Position Constraints
Create a position constraint and add it to a node.
Overview
You lock a node at a specific coordinate with positionX(_:y:). Constrain a node’s horizontal position with positionX(_:), or constrain its vertical position with positionY(_:).
The following code shows how you can create a node with an attached physics body that is affected by a noise field. The node moves with the noise but is constrained to a rectangular region between 300 and 340 points on both the horizontal and vertical axes.
scene.physicsWorld.gravity = CGVector(dx: 0, dy: 0)
let noiseField = SKFieldNode.noiseField(withSmoothness: 1, animationSpeed: 0.1)
scene.addChild(noiseField)
let node = SKShapeNode(circleOfRadius: 10)
node.physicsBody = SKPhysicsBody(circleOfRadius: 10)
scene.addChild(node)
let range = SKRange(lowerLimit: 300, upperLimit: 340)
let lockToCenter = SKConstraint.positionX(range, y: range)
node.constraints = [ lockToCenter ]