How to Detect Collision in Swift, Sprite Kit

How to Detect collision in Swift, Sprite kit

Define unique categories, ensure your class is a SKPhysicsContactDelegate and make yourself the physics contact delegate:

//Physics categories

let enemyCategory:    UInt32 = 1 << 1
let bulletCategory:   UInt32 = 1 << 2

class GameScene: SKScene, SKPhysicsContactDelegate {
   physicsWorld.contactDelegate = self

Assign the categories (usually in didMove(to view:) :
enemy.physicsBody.catgeoryBitMask = enemyCategory bullet.physicsBody.catgeoryBitMask = bulletCategory

(Make sure you've created physics bodies for each node)

Set up collisions:

enemy.physicsBody?.collisionBitMask = 0 // enemy collides with nothing
bullet.physicsBody?.collisionBitMask = 0 // bullet collides with nothing

or even:

for node in [enemy, bullet] {
   node.physicsBody?.collisionBitMask = 0 //  collides with nothing
   }

Set up contacts
bullet.physicsBody?.collisionBitMask = enemyCategory // bullet contacts enemy

Make sure that at least one of the objects involved in each potential contact has the isDynamic property on its physics body set to true, or no contact will be generated. It is not necessary for both of the objects to be dynamic.

You should now get didBegin called when the bullet and the enemy make contact. You could code didBegin 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 bulletCategory | enemyCategory:
        print("bullet and enemy have contacted.")
        let bulletNode = contact.bodyA.categoryBitMask == bulletCategory ? contact.bodyA.node : contact.bodyB.node
        enemyHealth -= 10
        bulletNode.removeFromParent
     default:
        print("Some other contact occurred")
     }

}

Collision Detection In Sprite Kit Swift

physicsBody!.isDynamic = false means that no physics activity will happen to this body. Other bodies can interact with it, but it will not interact with anything.

This makes sense for a pipe to have, because a pipe never moves, so there is no reason to be dynamic. (Your world should be moving, not the pipe, if you are doing a flappy bird-esc game)

Now for Mario, this does not make sense. Mario is a moving entity, so he will be interacting with the physics world around in. To fix your issue, you need to make him dynamic with mario.physicsBody!.isDynamic = true

SpriteKit Collision Detection Not Working Properly

Define unique categories, ensure your class is a SKPhysicsContactDelegate and make yourself the physics contact delegate:

//Physics categories

let appleCategory:   UInt32 = 1 << 0
let enemyCategory:    UInt32 = 1 << 1
let bulletCategory:   UInt32 = 1 << 2

class GameScene: SKScene, SKPhysicsContactDelegate {
   physicsWorld.contactDelegate = self

Assign the categories (usually in didMove(to view:) :
apple.physicsBody.catgeoryBitMask = appleCategory enemy.physicsBody.catgeoryBitMask = enemyCategory bullet.physicsBody.catgeoryBitMask = bulletCategory

(Make sure you've created physics bodies for each node)

Set up collisions:

apple.physicsBody?.collisionBitMask = 0 // apple/player collides with nothing enemy.physicsBody?.collisionBitMask = 0 // enemy collides with nothing bullet.physicsBody?.collisionBitMask = 0 // bullet collides with nothing

or even:

for node in [apple, enemy, bullet] {
   node.physicsBody?.collisionBitMask = 0 //  collides with nothing
   }

Set up contacts
bullet.physicsBody?.collisionBitMask = enemyCategory // bullet contacts enemy

You should now get didBegin called when the bullet and the enemy make contact. You could code didBegin 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 bulletCategory | enemyCategory:
        print("bullet and enemy have contacted.")
        let bulletNode = contact.bodyA.categoryBitMask == bulletCategory ? contact.bodyA.node : contact.bodyB.node
        enemyHealth -= 10
        bulletNode.removeFromParent
     default:
        print("Some other contact occurred")
     }

}

How to Detect Collision in Swift, Sprite Kit