如何快速连续测试位置条件？

Question

您可以从我的代码中看到，对象是否在移动取决于用户是否已注册长按。如果对象超出视野，我想在testPosition函数中执行代码，该函数只是将其重新放置在视野中。我不知道在哪里使用此功能。如果我以长按手势应用它，则只有在长按开始或结束时才进行测试，因此，如果用户一直按住，则该功能将不会执行，并且该对象也不会重新定位。我也尝试了while语句，但它们似乎也不起作用。欢迎提出任何建议，我对Swift还是一个新手，感谢您的帮助。

import SpriteKit


class GameScene: SKScene {

let square = SKSpriteNode(imageNamed: "square")

override func didMove(to view: SKView) {
    setScene()
}

@objc func press(_ sender: UILongPressGestureRecognizer) {
    sender.minimumPressDuration = 0.01
    if sender.state == .ended {
        physicsWorld.gravity = CGVector(dx: 0, dy: -1.7)
        print ("press ends")
        square.run(SKAction.applyForce(CGVector(dx: 0, dy: -275), duration: 0.3))
    } else if sender.state == .began {
        square.run(SKAction.applyForce(CGVector(dx: 0, dy: 275), duration: 0.3))
        physicsWorld.gravity = CGVector(dx: 0, dy: 1.7)
        print ("pressed")
    } else {
        return
    }
}

func testPosition() {
    if square.position.y < frame.minY {
        print("too low")
        square.position.y = frame.minY + 100
    } else if square.position.y > frame.maxY {
        print("too high")
        square.position.y = frame.maxY - 100
    } else {
        return
    }
}

func setScene() {
    backgroundColor = UIColor(red: 238/255, green: 12/255, blue: 95/255, alpha: 1.0)
    square.color = UIColor(red: 51/255, green: 51/255, blue: 51/255, alpha: 1.0)
    square.size = CGSize(width: frame.size.width/20, height: frame.size.width/20)
    square.position = CGPoint(x: frame.midX - 200, y: frame.midY+150)
    addChild(square)
    square.physicsBody = SKPhysicsBody(rectangleOf: square.size)
    square.physicsBody?.categoryBitMask = PhysicsCategories.squareCategory
    physicsWorld.gravity = CGVector(dx: 0, dy: -1.7)
    square.physicsBody?.affectedByGravity = true
    view?.addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: #selector(press)))

}
}

Answer 1

如下使用计划的计时器重复检查，

对于[SpriteKit]

// In the begin of Long Press, Call the following "startPositionChecking" Function
private func startPositionChecking() {

    let wait: SKAction = SKAction.wait(forDuration: 0.5) // ex: Each 0.5 Second
    let checkingAction: SKAction = SKAction.run {

        self.testPosition()

    }

    let sequence: SKAction = SKAction.sequence([wait, checkingAction])
    let checkingTimer = SKAction.repeatForever(sequence)
    self.run(checkingTimer, withKey: "checkingTimer")

}

// In the End of Long Press, Call the following "endPositionChecking" Function
private func endPositionChecking() {

  self.removeAction(forKey: "checkingTimer")

}

对于[SWIFT]

var checkingTimer: Timer?

private func startPositionChecking() {

  checkingTimer = Timer.scheduledTimer(timeInterval: 0.5, target: self, selector: #selector(testPosition), userInfo: nil, repeats: true)

}

private func endPositionChecking() {

 checkingTimer?.invalidate()

}