Unexpected categoryBitMask value with SpriteKit and Swift

I am trying to detect contact between two nodes in SpriteKit with Swift, but when contact was made, I got unexpected value for the categoryBitMask. With the following block of code, I should expected to get the value of 1 or 2 for bodyA, 3 or 4 for bodyB, instead of that, I got the value 1 or 2 for bodyA, but I got a value of 4294967295 for bodyB. Any ideas why this happened? and how I can fix it? Thanks.

func testAddingSprites() {

    var fallSprite = SKSpriteNode()
    let fallingShapeIndex = Int(arc4random_uniform(UInt32(fallingShape.count)))
    switch fallingShapeIndex {
    case 0:
        fallSprite = SKSpriteNode(imageNamed: "rectangle.png")
        fallObj.append(fallSprite)
        println(fallObj.count, fallingShapeIndex)
        fallSprite.physicsBody?.categoryBitMask = 3
        fallSprite.physicsBody?.contactTestBitMask = 1 | 2
    case 1:
        fallSprite = SKSpriteNode(imageNamed: "circle.png")
        fallObj.append(fallSprite)
        println(fallObj.count,fallingShapeIndex)
        fallSprite.physicsBody?.categoryBitMask = 4
        fallSprite.physicsBody?.contactTestBitMask = 1 | 2
    default:
        println("Unexpected fallingShapeIndex", fallingShapeIndex)
    }

    fallSprite.physicsBody = SKPhysicsBody(circleOfRadius: 50)
    fallSprite.position = CGPointMake(self.frame.width / 2, self.frame.height / 2 + 250)
    fallSprite.physicsBody?.dynamic = true
    fallSprite.physicsBody?.affectedByGravity = false

    self.addChild(fallSprite)

    // set fall object movment
    let moveAction = SKAction.moveTo(CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame) - 110), duration: 3)
    let cleanAction = SKAction.removeFromParent()
    fallSprite.runAction(SKAction.sequence([moveAction, cleanAction]), withKey: "fallObjMove")

}

Here are some solutions I already tried,

1. I tried to assign the categoryBitsMask by the following code, I got the same unexpected value.

   enum fallObjGroup:UInt32 {
       case rectangleFall = 1
       case circleFall = 2
   }
   enum matchObjGroup:UInt32 {
       case rectangleMatch = 1
       case circleMatch = 2
   }
   
   

2. I tried to clean build folder, and restart Xcode, no luck either.

EDIT: code for getting the value:

func didBeginContact(contact: SKPhysicsContact) {
    if contact.bodyA.categoryBitMask == 1 && contact.bodyB.categoryBitMask == 3 {

        println("rectangle contact made", Int(contact.bodyA.categoryBitMask),Int(contact.bodyB.categoryBitMask))

    } else if contact.bodyA.categoryBitMask == 2 && contact.bodyB.categoryBitMask == 4 {

        println("circle contact made", Int(contact.bodyA.categoryBitMask),Int(contact.bodyB.categoryBitMask))

    } else {

        println("GAME OVER!!!", Int(contact.bodyA.categoryBitMask),Int(contact.bodyB.categoryBitMask))

    }
}

Result: (GAME OVER!!!, 1, 4294967295) & (GAME OVER!!!, 2, 4294967295)