didBeginContact for three sprites works for 2 sprites, but not for the third one - Swift2 - ios

Question

I have a bird, multiple desks and a star. When the bird collides with one of the desks, the didBeginContact method works fine, but when it collides with the star, nothing happens. I will copy the code where I added some print statements so it is easier to see what is happening and then I will paste the print statements that it prints out.
Bird (just the initialization of the physicsBody part):
class Bird: SKSpriteNode {
var sc: SKScene!
init(sc: SKScene) {
let texture = SKTexture(imageNamed: "hero")
let size = texture.size()
self.sc = sc
super.init(texture: texture, color: UIColor.clearColor(), size: CGSizeMake(size.width/2, size.height/2))
self.zPosition = Layer.Bird.rawValue
self.name = "bird"
self.physicsBody = SKPhysicsBody(circleOfRadius: self.size.width/2)
self.physicsBody?.categoryBitMask = PhysicsCategory.Bird
self.physicsBody?.collisionBitMask = PhysicsCategory.Desk
self.physicsBody?.contactTestBitMask = PhysicsCategory.Desk | PhysicsCategory.StarSpecial | PhysicsCategory.Star
self.physicsBody?.allowsRotation = true
self.physicsBody?.restitution = 0
self.physicsBody?.usesPreciseCollisionDetection = true
}
// other methods and the required init
}
The star class is constructed the same way so I will just copy physicsBody related code:
self.physicsBody = SKPhysicsBody(circleOfRadius: self.size.width/2, center: self.position)
self.physicsBody?.affectedByGravity = false
self.physicsBody?.pinned = true
self.physicsBody?.categoryBitMask = PhysicsCategory.StarSpecial
self.physicsBody?.collisionBitMask = PhysicsCategory.None
self.physicsBody?.contactTestBitMask = PhysicsCategory.Bird
self.physicsBody?.usesPreciseCollisionDetection = true
self.physicsBody?.allowsRotation = false
self.physicsBody?.restitution = 0
self.physicsBody?.usesPreciseCollisionDetection = true
And the didBeginContact method in GameScene:
func didBeginContact(contact: SKPhysicsContact) {
print("something has collided")
if contact.bodyA.categoryBitMask == PhysicsCategory.Bird && contact.bodyB.categoryBitMask == PhysicsCategory.Desk {
birdSprite.BirdDidCollideWithDesk(contact.bodyA.node as! Bird, desk: contact.bodyB.node as! Desk, scoreClass: scoreClass, scoreLabel: scoreLabel)
print("bird and desk have collided")
} else if contact.bodyA.categoryBitMask == PhysicsCategory.Desk && contact.bodyB.categoryBitMask == PhysicsCategory.Bird {
print("desk and bird have collided")
birdSprite.BirdDidCollideWithDesk(contact.bodyB.node as! Bird, desk: contact.bodyA.node as! Desk, scoreClass: scoreClass, scoreLabel: scoreLabel)
}
if contact.bodyA.categoryBitMask == PhysicsCategory.Bird && contact.bodyB.categoryBitMask == PhysicsCategory.StarSpecial {
print("collided into star1")
starSpecial.removeStar(contact.bodyB.node as! Star)
} else if contact.bodyA.categoryBitMask == PhysicsCategory.StarSpecial && contact.bodyB.categoryBitMask == PhysicsCategory.Bird {
print("collided into star2")
starSpecial.removeStar(contact.bodyB.node as! Star)
}
}
If I run it, I get the following messages:
If the bird collides with a desk: "something has collided", "desk and bird have collided"
If the bird collides with the star: "something has collided"
Neither of second two conditions is met, so the message "collided into star1" or "collided into star2" is not printed out.
Any idea what could be causing this?