精灵跟随一个不同的精灵并延迟

我做了我的第一个应用程序,问题出现了,如何使一个物体以一定的速度跟随另一个物体,试图找到问题的答案,但没有找到。 这就是我所做的,但没有拖延

创造英雄和枪支。

 func createHero() {
 
    hero = SKSpriteNode(texture: heroTexture)
    
    //Anim hero
    heroTextureArray = [SKTexture(imageNamed: "hero.png"), SKTexture(imageNamed: "Fly1.png"), SKTexture(imageNamed: "Fly2.png"), SKTexture(imageNamed: "Fly3.png"), SKTexture(imageNamed: "Fly4.png")]
    let heroFlyAnimation = SKAction.animate(with: heroTextureArray, timePerFrame: 0.1)
    let flyHero = SKAction.repeatForever(heroFlyAnimation)
    hero.run(flyHero)
    
    hero.position = position
    hero.size.height = 60
    hero.size.width = 65
    
    hero.physicsBody?.isDynamic = true
    hero.physicsBody?.allowsRotation = false
    hero.zPosition = 1
    
    heroObject.addChild(hero)
}


 func createGuns(){
    
    gunsTexture = SKTexture(imageNamed: "guns")
    
    guns = SKSpriteNode(texture: gunsTexture)
    
    guns.zPosition = 1
    guns.position = CGPoint(x: self.frame.width/2, y: 0)
    guns.physicsBody?.isDynamic = true
    guns.size.height = 35
    guns.size.width = 40
    guns.zRotation = CGFloat(.pi/2.0)

    
    gunsObject.addChild(guns)
    
}

英雄运动

var flag = false

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
     let touch = touches.first
        let location = touch?.location(in: self)
    
        if (physicsWorld.body(at: location!) != nil) {
            
           flag = true
        
    }
}

 override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
     let touch = touches.first
     let touchLocation = touch!.location(in: self)
    let previousLocation = touch!.previousLocation(in: self)
    
    
    let hero = self.hero
    let guns = self.guns
    var heroX = hero.position.x + (touchLocation.x - previousLocation.x)
    
    heroX = max(heroX, hero.size.width / 2)
    heroX = min(heroX, size.width - hero.size.width / 2)
    
    var heroY = hero.position.y + (touchLocation.y - previousLocation.y)
    
    heroY = max(heroY, hero.size.height / 2 + 20)
    heroY = min(heroY, size.height - hero.size.height / 2)
    hero.position = CGPoint(x: heroX, y: heroY)
    guns.position = CGPoint(x: heroX, y: guns.position.y)
    guns.position = CGPoint(x: heroX, y: 20)
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    flag = false
}