ios swift collision detection

0
votes

I'm trying to build my first iOS swift game and I have some trouble in detection the collision between objects. I have some objects falling down, and another object on the bottom of the screen. I want to know when the falling objects touches the other object. So, here is what I have:

In my scene class (inside my init method):

player = SKSpriteNode(imageNamed: "playerImg")
    player.position = CGPointMake(gameBoard.size.width/2, -(gameBoard.size.height + 55))
    player.size = CGSize(width: 40,height: 40)
    player.physicsBody = SKPhysicsBody(rectangleOfSize: player.size)
    player.physicsBody?.dynamic = false
    player.physicsBody?.categoryBitMask = BodyType.bro.rawValue
    player.physicsBody?.contactTestBitMask = BodyType.bro.rawValue
    player.physicsBody?.affectedByGravity = true

In anther custom method I have (still in the same scene class):

let sprite = SKSpriteNode(texture: texture)

    sprite.position = pointForColumn(block.column, row: block.row - 2)
    block.sprite = sprite

    sprite.physicsBody = SKPhysicsBody(rectangleOfSize: sprite.size)
    sprite.physicsBody?.dynamic = false
    sprite.physicsBody?.categoryBitMask = BodyType.bro.rawValue
    sprite.physicsBody?.contactTestBitMask = BodyType.bro.rawValue
    sprite.physicsBody?.affectedByGravity = true

Here is my BodyType enum:

enum BodyType:UInt32 {

    case bro = 1
    case ground = 2
    case anotherBody1 = 4
    case anotherBody2 = 8
    case anotherBody3 = 16

}

And finally, inside my didMoveToView method I have:

physicsWorld.contactDelegate = self
    view.showsPhysics = true

So, I see the green border around my objects, but when they touch I have nothing inside the didBeginContact method (here attached a screenshot). Anyone, some idea about what is missing in order to have a trigger when collision detected ?

enter image description here

2
iosswiftcollision-detectioncollision

2 Answers

1
votes

I got it. I had to put 

        sprite.physicsBody?.dynamic = true
        sprite.physicsBody?.affectedByGravity = false

and after that it works like a charm.

0
votes

You're setting the contactTestBitMask, not the collisionBitMask. The former just makes SpriteKit notify you of contacts between bodies, but doesn't change anything in the physics simulation on contact. You need the latter for a contact to turn into a collision (and for the collision to be resolved, making the bodies stop or bounce off one another).