Swift 应用脉冲不工作

我有一个我不能冲动使用的SKShapeNode。我有什么问题？谢谢

代码：

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ball.physicsBody？.isDynamic=false

表示忽略脉冲和其他力。您需要将其设置为true

ball.physicsBody？.isDynamic=false

表示忽略脉冲和其他力。您需要将其设置为true

        var ball = SKShapeNode()

        ball.path = UIBezierPath(roundedRect: CGRect(x:-ballWidth/2, y: -ballHeight/2, width: ballWidth, height: ballHeight), cornerRadius: 64).cgPath
        ball.position = CGPoint(x: self.frame.width / 2, y: self.frame.height / 2)
        ball.physicsBody = SKPhysicsBody(circleOfRadius: CGFloat(ballWidth / 2));
        ball.physicsBody?.affectedByGravity = false
        ball.physicsBody?.isDynamic = false
        ball.physicsBody?.categoryBitMask = ballCategory
        ball.physicsBody?.collisionBitMask = enemyCategory
        ball.physicsBody?.contactTestBitMask = enemyCategory
        ball.isHidden = false
        ball.fillColor = UIColor.blue
        ball.strokeColor = UIColor.white
        ball.lineWidth = 10
        ball.name = "ball"
        ball.zPosition = 0



        addChild(ball)

        ball.physicsBody?.applyImpulse(CGVector(dx: 50, dy: 50))