在 swift 中移动吃豆子

Question

我是 swift 的新手，我正在尝试编写吃豆人程序。我正在尝试将 pacman 移动到滑动的方向，到目前为止我已经设法将它移动到屏幕的边缘，问题是当我尝试将它移动时不是从屏幕边缘而是在中间在滑动动作中，它只是走到屏幕边缘并移动到滑动方向，这是一个方向的代码：

    var x = view.center.x
    for var i = x; i > 17; i--
    {
        var origin: CGPoint = self.view.center
        var move = CABasicAnimation(keyPath:"position.x")
        move.speed = 0.13
        move.fromValue = NSValue(nonretainedObject: view.center.x)
        move.toValue = NSValue(nonretainedObject: i)
        view.layer.addAnimation(move, forKey: "position")
        view.center.x = i
    }

问题是我知道问题是当我滑动到我想要的方向时 for 循环不会等待动画停止但它会在不到一秒的时间内完成循环我需要排序此处或其他代码的延迟。

Answer 1

这个问题很有趣，所以我决定用 SpriteKit 做一个例子。没有任何碰撞检测、路径查找甚至路径。这只是一个示例，说明如何在发生滑动时 'Pac-Man' 改变方向。

我已经包含了下面的 GameScene：

class GameScene: SKScene {
    enum Direction {
        case Left
        case Right
        case Up
        case Down
    }
    lazy var openDirectionPaths = [Direction: UIBezierPath]()
    lazy var closedDirectionPaths = [Direction: UIBezierPath]()
    lazy var wasClosedPath = false
    lazy var needsToUpdateDirection = false
    lazy var direction = Direction.Right
    lazy var lastChange: NSTimeInterval = NSDate().timeIntervalSince1970

    var touchBeganPoint: CGPoint?
    let pacmanSprite = SKShapeNode(circleOfRadius: 15)

    override func didMoveToView(view: SKView) {
        let radius: CGFloat = 15, diameter: CGFloat = 30, center = CGPoint(x:radius, y:radius)
        func createPaths(startDegrees: CGFloat, endDegrees: CGFloat, inout dictionary dic: [Direction: UIBezierPath]) {
            var path = UIBezierPath(arcCenter: center, radius: radius, startAngle: startDegrees.toRadians(), endAngle: endDegrees.toRadians(), clockwise: true)
            path.addLineToPoint(center)
            path.closePath()
            dic[.Right] = path
            for d: Direction in [.Up, .Left, .Down] {
                path = path.pathByRotating(90)
                dic[d] = path
            }
        }
        createPaths(35, 315, dictionary: &openDirectionPaths)
        createPaths(1, 359, dictionary: &closedDirectionPaths)
        pacmanSprite.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
        pacmanSprite.fillColor = UIColor.yellowColor()
        pacmanSprite.lineWidth = 2
        if let path = openDirectionPaths[.Right] {
            pacmanSprite.path = path.CGPath
        }
        pacmanSprite.strokeColor = UIColor.blackColor()
        self.addChild(pacmanSprite)
        updateDirection()

        // Blocks to stop 'Pacman' changing direction outside of a defined path?
        //375/25 = 15 width
        //666/37 = 18 height
    }

    override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
        touchBeganPoint = positionOfTouch(inTouches: touches)
    }

    override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
        if let touchStartPoint = touchBeganPoint,
            touchEndPoint = positionOfTouch(inTouches: touches) {
                if touchStartPoint == touchEndPoint {
                    return
                }
                let degrees = atan2(touchStartPoint.x - touchEndPoint.x,
                    touchStartPoint.y - touchEndPoint.y).toDegrees()
                var oldDirection = direction
                switch Int(degrees) {
                case -135...(-45):  direction = .Right
                case -45...45:      direction = .Down
                case 45...135:      direction = .Left
                default:            direction = .Up
                }
                if (oldDirection != direction) {
                    needsToUpdateDirection = true
                }
        }
    }

    override func touchesCancelled(touches: Set<NSObject>!, withEvent event: UIEvent!) {
        touchBeganPoint = nil
    }

    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
        if let nodes = self.children as? [SKShapeNode] {
            for node in nodes {
                let p = node.position
                let s = node.frame.size
                //let s = node.size
                if p.x - s.width > self.size.width {
                    node.position.x = -s.width
                }
                if p.y - s.height > self.size.height {
                    node.position.y = -s.height
                }
                if p.x < -s.width {
                    node.position.x = self.size.width + (s.width / 2)
                }
                if p.y < -s.height {
                    node.position.y = self.size.height + (s.height / 2)
                }
                if needsToUpdateDirection || NSDate().timeIntervalSince1970 - lastChange > 0.25 {
                    if let path = wasClosedPath ? openDirectionPaths[direction]?.CGPath : closedDirectionPaths[direction]?.CGPath {
                        node.path = path
                    }
                    wasClosedPath = !wasClosedPath
                    lastChange = NSDate().timeIntervalSince1970
                }
                updateDirection()
            }
        }
    }

    // MARK:- Helpers

    func positionOfTouch(inTouches touches: Set<NSObject>) -> CGPoint? {
        for touch in (touches as! Set<UITouch>) {
            let location = touch.locationInNode(self)
            return location
        }
        return nil
    }

    func updateDirection() {
        if !needsToUpdateDirection {
            return
        }
        pacmanSprite.removeActionForKey("Move")
        func actionForDirection() -> SKAction {
            let Delta: CGFloat = 25
            switch (direction) {
            case .Up:
                return SKAction.moveByX(0.0, y: Delta, duration: 0.1)
            case .Down:
                return SKAction.moveByX(0.0, y: -Delta, duration: 0.1)
            case .Right:
                return SKAction.moveByX(Delta, y: 0.0, duration: 0.1)
            default:
                return SKAction.moveByX(-Delta, y: 0.0, duration: 0.1)
            }
        }
        let action = SKAction.repeatActionForever(actionForDirection())
        pacmanSprite.runAction(action, withKey: "Move")
        needsToUpdateDirection = false
    }
}

存储库可以是 found here

我已经添加了 MIT 许可证，因此您可以根据需要创建此存储库。希望对您有所帮助。

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