How can I animate a SKPhysicsBody texture to match an SKTextureAtlas - swift

Question

I implemented #mfessenden suggestion regarding using a custom SKAction to match the SKPhysicsBody to follow the animation using alphaThreshold. ( https://stackoverflow.com/a/54096147 ) But it does not appear to be functioning for me. Where have I gone wrong? Can you help #mfessenden?
var rockFrames: [SKTexture] = []
let rockAnimatedAtlas = SKTextureAtlas(named: "funny")
let numImages = rockAnimatedAtlas.textureNames.count
for i in 1...numImages {
let rockTextureName = "\(i)"
rockFrames.append(rockAnimatedAtlas.textureNamed(rockTextureName))
}
let firstFrameTexture = rockFrames[0]
rock = SKSpriteNode(texture: firstFrameTexture)
rock.position = CGPoint(x: self.frame.midX, y: self.frame.midY + 100)
rock.size = CGSize(width: 480 * wR, height: 270 * hR)
self.addChild(rock)
let rockaction = SKAction.animate(with: rockFrames,
timePerFrame: (1/24),
resize: false,
restore: true)
rock.run(SKAction.repeatForever(rockaction))
typealias Frame = (texture: SKTexture, duration: TimeInterval)
let timePerFrame: TimeInterval = 1/24
let dogFrames: [Frame] = rockFrames.map {
return ($0, timePerFrame)
}
rock = SKSpriteNode(texture: rockFrames.first)
let dogAnimationAction = animateTexturesWithPhysics(dogFrames)
rock.run(dogAnimationAction)
public func animateTexturesWithPhysics(_ frames: [(texture: SKTexture, duration: TimeInterval)], repeatForever: Bool=true) -> SKAction {
var actions: [SKAction] = []
for frame in frames {
// define a custom action for each frame
let customAction = SKAction.customAction(withDuration: frame.duration) { node, _ in
// if the action target is a sprite node, apply the texture & physics
if node is SKSpriteNode {
let setTextureGroup = SKAction.group([
SKAction.setTexture(frame.texture, resize: false),
SKAction.wait(forDuration: frame.duration),
SKAction.run {
node.physicsBody = SKPhysicsBody(texture: frame.texture, alphaThreshold: 0.5, size: frame.texture.size())
node.physicsBody?.isDynamic = false
node.physicsBody?.categoryBitMask = self.arrowCategory
// add physics attributes here
}
])
node.run(setTextureGroup)
}
}
actions.append(customAction)
}
// add the repeating action
if (repeatForever == true) {
return SKAction.repeatForever(SKAction.sequence(actions))
}
return SKAction.sequence(actions)
}