SwiftのGameplayKitでAIに追いかける、避ける、逃げる処理を追加するには：ゲームの「敵」キャラで分かる「人工知能」の作り方（2）（4/4 ページ）

class GameScene: SKScene {
    // 省略
 
    func createEnemy() {
        // ここから今回追加
        guard let viewFrame = view?.frame else {
            return
        }
        let xDistribution = GKShuffledDistribution(lowestValue: -Int(viewFrame.width / 2), highestValue: Int(viewFrame.width / 2))
        let yDistribution = GKShuffledDistribution(lowestValue: -Int(viewFrame.height / 2), highestValue: Int(viewFrame.height / 2))
        // ここまで今回追加
 
        let enemy = SKShapeNode(circleOfRadius: 10)
        enemy.position.x = CGFloat(xDistribution.nextInt()) // 今回修正
        enemy.position.y = CGFloat(yDistribution.nextInt()) // 今回修正
        enemy.fillColor = UIColor(red: 0.94, green: 0.14, blue: 0.08, alpha: 1.0)
        enemy.physicsBody = SKPhysicsBody(circleOfRadius: enemy.frame.width / 2)
        addChild(enemy)
        enemies.append(enemy)
 
        let anemyAgent = GKAgent2D()
        anemyAgent.maxAcceleration = 200
        anemyAgent.maxSpeed = 70
        anemyAgent.position = vector_float2(x: Float(enemy.position.x), y: Float(enemy.position.y))
        anemyAgent.delegate = self
        anemyAgent.behavior = GKBehavior(goals: [
            GKGoal(toSeekAgent: playerAgent),
            GKGoal(toAvoid: obstacles, maxPredictionTime: 10),
            GKGoal(toFleeAgent: sweeperAgent)
            ], andWeights: [NSNumber(value: 5), NSNumber(value: 50), NSNumber(value: 1)])
        agentSystem.addComponent(anemyAgent)
        enemyAgents.append(anemyAgent)
 
        let goals = enemyAgents.map { GKGoal(toSeekAgent: $0) }
        sweeperAgent.behavior = GKBehavior(goals: goals + [GKGoal(toAvoid: obstacles, maxPredictionTime: 10)])
    }
 
    // 省略
}