如何实现 SpriteKit 计时器? [英] How to implement a SpriteKit timer?

问题描述

我目前正在尝试为我的 sprite kit 游戏实现计时器，但我没有得到它的工作.计时器的初始值始终保持不变.

I am currently trying to implement a timer for my sprite kit game, but I don't get it working. The initial value of the timer always remains the same.

我假设我需要以某种方式/某处更新标签，但我不知道 HOW 和 WHERE :?我不明白这一点.有什么想法吗?

I am assuming I need to update the label somehow/somewhere, but I don't know HOW and WHERE :? I don't get the point. Any ideas?

这是我的 GameScene 类中的代码

Here is my code within my GameScene Class

    let levelTimerLabel = SKLabelNode(fontNamed: "Chalkduster")
var levelTimerValue: Int  = 500

var levelTimer = NSTimer()

func startLevelTimer() {

    levelTimerLabel.fontColor = SKColor.blackColor()
    levelTimerLabel.fontSize = 40
    levelTimerLabel.position = CGPoint(x: size.width/2, y: size.height/2 + 350)
    addChild(levelTimerLabel)

    levelTimer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: Selector("levelCountdown"), userInfo: nil, repeats: true)

    levelTimerLabel.text = String(levelTimerValue)

}

func levelCountdown(){

    levelTimerValue--

}

推荐答案

我会坚持使用 SKActions 来完成 SpriteKit 中的这些任务，因为 NSTimer 不是受场景或视图暂停状态的影响，因此可能会给您带来麻烦.或者至少，它会要求您实现暂停功能，以便在某些情况下暂停您的计时器，例如当用户暂停场景或接听电话等时.阅读更多 这里 关于 SKAction vs NSTimer vs GCDSpriteKit 中与时间相关的操作.

I would stick to SKActions for these kind of tasks in SpriteKit due to fact that NSTimer is not affected by scene's, or view's paused state, so it might lead you into troubles. Or at least, it will require from you to implement a pause feature in order to pause your timers in certain situations, like when user pause the scene, or receive a phone call etc. Read more here about SKAction vs NSTimer vs GCD for time related actions in SpriteKit.

import SpriteKit

class GameScene: SKScene {

var levelTimerLabel = SKLabelNode(fontNamed: "ArialMT")

//Immediately after leveTimerValue variable is set, update label's text
var levelTimerValue: Int = 500 {
    didSet {
        levelTimerLabel.text = "Time left: (levelTimerValue)"
    }
}

override func didMoveToView(view: SKView) {



levelTimerLabel.fontColor = SKColor.blackColor()
levelTimerLabel.fontSize = 40
levelTimerLabel.position = CGPoint(x: size.width/2, y: size.height/2 + 350)
levelTimerLabel.text = "Time left: (levelTimerValue)"
addChild(levelTimerLabel)

    let wait = SKAction.waitForDuration(0.5) //change countdown speed here
    let block = SKAction.runBlock({
        [unowned self] in

        if self.levelTimerValue > 0{
            self.levelTimerValue--
        }else{
            self.removeActionForKey("countdown")
        }
    })
    let sequence = SKAction.sequence([wait,block])

    runAction(SKAction.repeatActionForever(sequence), withKey: "countdown")
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {

    //Stop the countdown action

    if actionForKey("countdown") != nil {removeActionForKey("countdown")}
}
}

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