How to determine a life to an object spritekit

Hello,

I start in spritekit and currently my player fires bullets at exploding enemies when there is a contact between the "bullet" and the "enemy"

Now I would like this one to explode only when I shoot 5 times, but I do not know how to do it. Can you help me ?

here is a small part of my code:

let VoitureCategory:UInt32 = 0b01 //1
    let BallesCategory:UInt32 = 0b10000 //16



        Enemis.physicsBody = SKPhysicsBody(rectangleOf: Enemis.size)
        Enemis.physicsBody?.isDynamic = true
 
        Enemis.physicsBody?.categoryBitMask = VoitureCategory
        Enemis.physicsBody?.contactTestBitMask = BallesCategory | PlayerCategoryContact | MurCategoryContact
 
        Enemis.physicsBody?.collisionBitMask = MurCategoryContact
        self.addChild(Enemis)



            BalleFusilNode.physicsBody = SKPhysicsBody(circleOfRadius: BalleFusilNode.size.width / 2)
            BalleFusilNode.physicsBody?.isDynamic = true
      
            BalleFusilNode.physicsBody?.categoryBitMask = BallesCategory
            BalleFusilNode.physicsBody?.contactTestBitMask = VoitureCategory
            BalleFusilNode.physicsBody?.collisionBitMask = VoitureCategory
            BalleFusilNode.physicsBody?.usesPreciseCollisionDetection = true
      
            self.addChild(BalleFusilNode)




    func didBegin(_ contact: SKPhysicsContact) {

        let collision = contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask
        if collision == VoitureCategory | BallesCategory {
            GestionContactBalleEtEnemisQuelconque(BalleFusilNode: contact.bodyA.node as! SKSpriteNode, EnemisNode: contact.bodyB.node as! SKSpriteNode)
        }
}

    func GestionContactBalleEtEnemisQuelconque (BalleFusilNode:SKSpriteNode, EnemisNode:SKSpriteNode) {
       
        let explosion = SKEmitterNode(fileNamed: "Explosion")!
        explosion.position = EnemisNode.position
        self.addChild(explosion)
       
        self.run(SKAction.playSoundFileNamed("explosion1.mp3", waitForCompletion: false))
       
        BalleFusilNode.removeFromParent()
        EnemisNode.removeFromParent()
       
        explosion.zPosition = 5
       
        self.run(SKAction.wait(forDuration: 0.5)) {
            explosion.removeFromParent()
        }
       
        score += 1
       
       
    }

thank you,