Almost everything is done now, and in this final section, we are going to add the correct interaction between all the elements of the game.
When the bird touches a pipe, we need to push it down so that it touches the ground and dies:
extension GameScene: SKPhysicsContactDelegate {
func didBeginContact(contact: SKPhysicsContact!) {
//...
case BodyType.pipe.rawValue | BodyType.bird.rawValue:
println("Contact with a pipe")
bird.pushDown()
//...
}To push it, we can use the same technique that we used for the flapping—applying an impulse:
func pushDown() {
dying = true
node.physicsBody!.applyImpulse(CGVector(dx: 0, dy: -10))
}Although the impulse has been applied correctly, you might notice that you can continue flapping after touching a pipe, and sometimes the bird starts flying again.
To solve this issue, we add a status variable to the bird. This variable indicates whether the bird is dying or is alive:
class...