SKPhysicsBody Collision Not Working

6
votes

Below is my "Floor.swift" class below which is basically a bunch of walls. I have objects coming from the top of the screen and once the Floor and SKSpriteNodes collide, I'd like the SKSpriteNode to be removed. Below is my Floor class.

import Foundation
import SpriteKit

class Floor: SKNode {
    override init() {
        super.init()

        let leftWall = SKSpriteNode(color: UIColor.clear, size: CGSize(width: 5, height: 50))
        leftWall.position = CGPoint(x: 0, y: 50)
        leftWall.physicsBody = SKPhysicsBody(rectangleOf: leftWall.size)
        leftWall.physicsBody!.isDynamic = false
        self.addChild(leftWall)

        let rightWall = SKSpriteNode(color: UIColor.clear, size: CGSize(width: 5, height: 50))
        rightWall.position = CGPoint(x: 375, y: 50)
        rightWall.physicsBody = SKPhysicsBody(rectangleOf: rightWall.size)
        rightWall.physicsBody!.isDynamic = false
        self.addChild(rightWall)

        let bottomWall = SKSpriteNode(color: UIColor.clear, size: CGSize(width: 500, height: 10))
        bottomWall.position = CGPoint(x: 150, y: -5)
        bottomWall.physicsBody = SKPhysicsBody(rectangleOf: bottomWall.size)
        bottomWall.physicsBody!.isDynamic = false
        self.addChild(bottomWall)

        self.physicsBody = SKPhysicsBody(bodies: [leftWall.physicsBody!, rightWall.physicsBody!, bottomWall.physicsBody!])

        self.physicsBody?.categoryBitMask = floorCategory
        self.physicsBody?.contactTestBitMask = nailDropCategory | pointCategory | lifeCategory
        self.physicsBody?.collisionBitMask = balloonCategory
    }

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

GameScene class under "func didBegin(_ contact: SKPhysicsContact)" I wrote:

func didBegin(_ contact: SKPhysicsContact) {        
        if (contact.bodyA.categoryBitMask == nailDropCategory | pointCategory | lifeCategory) && (contact.bodyB.categoryBitMask == floorCategory) {
           // contact.bodyB.node!.removeFromParent()
            print("COLLISION")
        }
}

As you can see, in my Floor class I set the object as "self.physicsBody = SKPhysicsBody(bodies:)" with all my SKSpriteNode. But for some reason I'm not getting any detection what's so ever. I made my "Floor" class be a "contactTestBitMask" on each class of my objectCategory, pointCategory, lifeCategory. This has been an issue I've been stuck on for a minute now, any ideas?

Update:

So I'm using this code below now and it's working! Only issue is, the default case is removing my "balloonCategory" also and I don't want it to do that. How can I make it ignore only that category but also act as a wall to the balloon? 

func didBegin(_ contact: SKPhysicsContact) {
        let contactMask = contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask

        switch contactMask {
        case balloonCategory | nailDropCategory:
            print("nailDrop and balloon have contacted.")
            contact.bodyB.node!.removeFromParent()
            self.run(SKAction.playSoundFileNamed("lostlifesound.mp3", waitForCompletion:false))
            lifeLost -= 1
        case balloonCategory | pointCategory:
            print("point and balloon have contacted.")
            contact.bodyB.node!.removeFromParent()
            totalPoints += 2
            self.run(SKAction.playSoundFileNamed("pointsound.mp3", waitForCompletion:false))
        case balloonCategory | lifeCategory:
            print("life and balloon have contacted.")
            contact.bodyB.node!.removeFromParent()
            lifeLost += 1
            self.run(SKAction.playSoundFileNamed("pointsound.mp3", waitForCompletion:false))
        default:            
            contact.bodyB.node!.removeFromParent()
            print("Removed \(String(describing: contact.bodyB.node!.name))")
        }
    }
2
swiftsprite-kitskphysicsbody
nailDropCategory? pointCategory? lifeCategory? Nobody but you knows how you define your bit masks. – El Tomato
Well, I defined it on all my other classes and all the other collisions works so I’m just lost lol – Dewan
If physics is already working in your project then seems like this should work. Are you able to reproduce this issue in a sample project & share on Github? Seems like the solution may come from debugging. – peacetype
@peacetype Take a look at my code update. I'm using the switch method now. In the default: section, it's removing all other nodes which is perfect but I don't want it to remove my balloonCategory but I also don't want it to remove the balloonCategory when it collides with my floorCategory. I just want it to act as a wall to it. How can I do that? – Dewan
@Dewan. You can't always remove the nodeB object, because you don't know which object is nodeA and which is nodeB, but there is an easy way to resolve this. Can you tell me which node(s) do you want removed for each contact? – Steve Ives

2 Answers

5
votes

It sounds like you would benefit from assigning names to all your object types, like so: 

class Balloon: SKSpriteNode {
    init() {
        super.init(texture: nil, color: .blue, size: CGSize(width: 50, height: 50))
        self.name = "balloon"
    }
}

Now when you make your check in the switch, you can verify the identity of objects before deciding to delete them. See the change I made to the default case in your switch statement, below. This way, the node will not be removed if it is a balloon. The physics collisions will continue to work.

func didBegin(_ contact: SKPhysicsContact) {
    let contactMask = contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask

    switch contactMask {
    case balloonCategory | nailDropCategory:
        print("nailDrop and balloon have contacted.")
        contact.bodyB.node!.removeFromParent()
        self.run(SKAction.playSoundFileNamed("lostlifesound.mp3", waitForCompletion:false))
        lifeLost -= 1
    case balloonCategory | pointCategory:
        print("point and balloon have contacted.")
        contact.bodyB.node!.removeFromParent()
        totalPoints += 2
        self.run(SKAction.playSoundFileNamed("pointsound.mp3", waitForCompletion:false))
    case balloonCategory | lifeCategory:
        print("life and balloon have contacted.")
        contact.bodyB.node!.removeFromParent()
        lifeLost += 1
        self.run(SKAction.playSoundFileNamed("pointsound.mp3", waitForCompletion:false))
    default:
        if contact.bodyB.node!.name == "balloon" {
            print("Balloon collided but we will not remove it.")
            return
        } else {
            contact.bodyB.node!.removeFromParent()
            print("Removed \(String(describing: contact.bodyB.node!.name))")
    }
}
1
votes

You can't guarantee that nodeB is the floor and is nodeA really nailDropCategory | pointCategory | lifeCategory?

I'm assuming that naildDrop, point and life are 3 objects that you want to be notified for when any one touches the floor, so try structuring your didBegin(contact:) like this:

  func didBegin(_ contact: SKPhysicsContact) {
     print("didBeginContact entered for \(String(describing: contact.bodyA.node!.name)) and \(String(describing: contact.bodyB.node!.name))")

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

     switch contactMask {
     case nailDropCategory | FloorCategory:
        print("nailDrop and floor have contacted.")
     case pointCategory | FloorCategory:
        print("point and floor have contacted.")
     case lifeCategory | FloorCategory:
        print("life and floor have contacted.")
     default:
        print("Undetected collision occurred")
     }
 }

Have you actually created an object from your Floor class?