contacts not recognized when body is changed from circle to rectangle - swift

Question

With help from here I have made a circle body traverse a given path. I have some bodies at some of the path points and have logged contact in didBeginContact. When the body gets in contact with a specific body the circle body is changed to a rectangle. This rectangular body is suppose to traverse the same path as the original circle body but it doesn't reach the path points as the contact is not logged. I tried changing radiusPoint to the width or height of the rectangle also but that didn't work. Also the rectangle body is bigger than the circle body. How can I get the rectangle to traverse the points with the contact recognised? Please see code below.
Code related to path traversal:
let repeats: Bool = true //Whether to repeat the path.
var pathIndex = 0 //The index of the current point to travel.
var pointRadius: CGFloat = SKTexture(imageNamed: "circle").size().width //How close the node must be to reach the destination point.
let travelSpeed: CGFloat = 250 //Speed the node will travel at.
let rate: CGFloat = 0.9 //Motion smoothing. 0.5
circlePath = [
CGPoint(x:screenSize.width , y: screenSize.height/3),
CGPoint(x: screenSize.width/2, y: platform.sprite.frame.height),
CGPoint(x: 0.0, y: screenSize.height/3),
CGPoint(x: CGFloat(pos1) + screenSize.width/20, y: upperSpearPosHeight)]
final func didReachPoint() {
//reached point!
pathIndex++
if pathIndex >= ballPath.count && repeats {
pathIndex = 0
}
}
func updatePath() {
if pathIndex >= 0 && pathIndex < circlePath.count {
let destination = circlePath[pathIndex]
//currentPosition = destination
let displacement = CGVector(dx: destination.x-circle!.sprite.position.x, dy: destination.y-circle!.sprite.position.y)
let radius = sqrt(displacement.dx*displacement.dx+displacement.dy*displacement.dy)
let normal = CGVector(dx: displacement.dx/radius, dy: displacement.dy/radius)
let impulse = CGVector(dx: normal.dx*travelSpeed, dy: normal.dy*travelSpeed)
let relativeVelocity = CGVector(dx:impulse.dx-circle!.sprite.physicsBody!.velocity.dx, dy:impulse.dy-circle!.sprite.physicsBody!.velocity.dy);
circle!.sprite.physicsBody!.velocity=CGVectorMake(circle!.sprite.physicsBody!.velocity.dx+relativeVelocity.dx*rate, circle!.sprite.physicsBody!.velocity.dy+relativeVelocity.dy*rate);
if radius < pointRadius {
didReachPoint()
}
}
}
Contact code:
func didBeginContact(contact: SKPhysicsContact) {
var firstBody : SKPhysicsBody
var secondBody : SKPhysicsBody
if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
firstBody = contact.bodyA
secondBody = contact.bodyB
}
else {
firstBody = contact.bodyB
secondBody = contact.bodyA
}
if firstBody.categoryBitMask == circleCategory && secondBody.categoryBitMask == bonusCategory {
let img = SKTexture(imageNamed: "rectangular")
(firstBody.node! as? SKSpriteNode)?.size = img.size()
firstBody.node!.physicsBody = SKPhysicsBody(texture: img, size: img.size())
firstBody.node!.physicsBody?.allowsRotation = false
changeCircleAction = SKAction.setTexture(img)
firstBody.node!.runAction(changeCircleAction)
}
if firstBody.categoryBitMask == circleCategory && secondBody.categoryBitMask == platformCategory {
print("touched platform")
}
if firstBody.categoryBitMask == circleCategory && secondBody.categoryBitMask == smallStarCategory {
removeStar(secondBody.node!)
}

Answer 1

It seems like when you change the firstBody to a rectangle (in the didBeginContact method), you don't set the bit mask. From what you described, it appears you want to set it to circleCategory as such:
firstBody.node!.physicsBody?.categoryBitMask = circleCategory
I would put this right below the firstBody.node!.physicsBody?.allowsRotation = false.