使用多个 didBegin 联系人 - SpriteKit

Question

I would like to have so SKSpriteNodes can take care of there own contact detection. Much like Unity have there own OnTriggerEnter methods on there GameObjects. But I do not know how to achieve that in SpriteKit, some help would much appriciated

Example how I would "like" it to work:

example Ball class:

import SpriteKit

class Ball: SKSpriteNode, SKPhysicsContactDelegate {

    func didBegin(_ contact: SKPhysicsContact) {
        print("INSIDE BALL: ",contact.bodyA.node?.name, contact.bodyB.node?.name)
    }

    init(x: Int, y: Int) {
physicsWorld.contactDelegate = self ????

     //setting up Physicsbody etc
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

}

example scene file

import SpriteKit
import GameplayKit

class GameScene: SKScene, SKPhysicsContactDelegate {

    override func didMove(to view: SKView) {
        physicsWorld.contactDelegate = self
    }


    func didBegin(_ contact: SKPhysicsContact) {
        print("INSIDE MAIN: ",contact.bodyA.node?.name, contact.bodyB.node?.name)
    }

Or how do you manage large amount of contact logic?

Thanks for any help and sorry if the questions is weirdly formulated

Answer 1

I like to structure my didBegin code this way: (the objects that can contact are blueBall, blueRectangle, greenBall, greenRectangle, redBall and redRectangle)

func didBegin(_ contact: SKPhysicsContact) {

    let contactMask = contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask

    switch contactMask {

    case blueBallCategory | blueRectangleCategory:
       print("Alive! Blue ball has hit blue rectangle.")

    case greenBallCategory | greenRectangleCategory:
       print("Alive! Green ball has hit green rectangle.")

    case redBallCategory | redRectangleCategory:
       print("Alive! Red ball has hit red rectangle.")

    default :
        print("Dead! Some other contact has occurred")
    }
}

You could, of course, call separate functions inside each case statement if you have much more contact logic. Equally you could call a collision method in the object that has collided:

    case blueBallCategory | blueRectangleCategory:
       contact.bodyA.hasHit(contact.bodyB)

or similar.