多个 SKSpriteNode 的 SpriteKit 多个 SKActions - 等待全部完成

Question

我正在开发一款 iOs 游戏，但遇到了问题。 我需要显示 x 个精灵（每个精灵都有一个比例 SKAction）。 我需要能够等到所有 SKAction 精灵然后再做其他事情。 每个 SKAction 在单独的线程中运行。 我怎么能等呢？

这是一段代码：

for tile in tiles {

            let randomNum:UInt32 = arc4random_uniform(20) // range is 0 to 99
            let randomTime:TimeInterval = TimeInterval(randomNum/10)
            let scale = SKAction.scale(by: 1, duration: 2, delay:randomTime , usingSpringWithDamping: 0.1, initialSpringVelocity: 5)

            tile.sprite = SKSpriteNode(imageNamed: tile.type.spriteName)
            tile.sprite?.size = CGSize(width: TileWidth, height: TileHeight)
            tile.sprite?.position = tile.position!

            tile.sprite?.scale(to: CGSize(width: 0, height: 0))
            cookiesLayer.addChild(tile.sprite!)
            tile.sprite?.run(scale)


        }
//TODO code to add to be executed after all SKActions

在所有 SKActions 之后，我怎样才能让我的 TODO 代码成为执行者？ 我想并行或一个接一个地运行 SKAction。

谢谢。

Answer 1

您可以在 run 方法中使用完成块很容易地做到这一点。

就本示例而言，假设您有一个名为 someSpriteNode 的 SKSpriteNode 并想知道两个操作（在这种情况下为 applyImpulse）何时完成运行：

    // 1) Create your actions:

    let action1 = SKAction.applyImpulse(CGVector(dx: 1.0, dy: 0.0), duration: 2.0)
    let action2 = SKAction.applyImpulse(CGVector(dx: 6.0, dy: 2.0), duration: 1.0)

     // 2) Add them to a sequence:

    let actionSequence = SKAction.sequence([action1, action2])

     // 3) Run the sequence using a completion block:

    someSpriteNode?.run(actionSequence, completion: {

         // All your actions are now finished

         // Do whatever you want here :)
    })

更新：在执行一组操作时收到通知，所有操作都在同一个节点上运行

那么您可能正在寻找行动组：

// Declare an empty array that will store all your actions:

var actions = [SKAction]()

// Iterate through your nodes:

for _ in 0..<6 {

    // ...

    // Generate your random scale, delay, or whatever you need:

    let randomScale = CGFloat(GKRandomDistribution(lowestValue: 0, highestValue: 10).nextInt())

    // Create your custom action

    let scaleAction = SKAction.scale(by: randomScale, duration: 2.0)

    // Append your action to the actions array:

    actions.append(scaleAction)
}


// Create an action group using the actions array:

let actionGroup = SKAction.group(actions)

// Run your action group, and do whatever you need inside the completion block:

self.run(actionGroup, completion: {

    // All your actions are now finished, no matter what node they were ran on.
})

另外，我建议你在游戏中使用GameplayKit 来生成随机数，它肯定会让你的生活更轻松:)

更新 2：在所有操作都在不同节点上运行的情况下，在所有操作都执行时收到通知

使用DispatchGroup：

    // Create a DispatchGroup:

    let dispatchGroup = DispatchGroup()

    for _ in 0..<6 {

        // ...

        let randomWait = Double(GKRandomDistribution(lowestValue: 1, highestValue: 12).nextInt())

        let waitAction = SKAction.wait(forDuration: randomWait)
        let fadeOutAction = SKAction.fadeOut(withDuration: 2.0)
        let fadeInAction = SKAction.fadeIn(withDuration: 2.0)
        let sequenceAction = SKAction.sequence([waitAction, fadeOutAction, fadeInAction])

        // Enter the DispatchGroup

        dispatchGroup.enter()

        colorSquares[i].run(sequenceAction, completion: {

             // Leave the DispatchGroup

             dispatchGroup.leave()
        })

    }

   // Get notified when all your actions left the DispatchGroup:

    dispatchGroup.notify(queue: DispatchQueue.main, execute: {

        // When this block is executed, all your actions are now finished
    })

我认为这个解决方案比计数器更优雅:)

Answer 2

首先，您应该始终创建一个Minimum Verifiable Example。从您的问题中删除不需要的内容，并确保包含我们测试您的代码所需的所有内容。

前提

我假设你有一个类似的 Tile 类

class Tile {
    var sprite: SKSpriteNode?
}

还有这样的数组

let tiles:[Tile] = ...

你的目标

1. 您希望对瓷砖中每个瓷砖的精灵元素运行一个随机持续时间的动作。
2. 您希望操作同时开始
3. 您希望能够在所有操作完成后运行一些代码

解决方案

// 0. create a maxDuration variable
var maxDuration:TimeInterval = 0

// 1. create all the actions
let actions = tiles.map { tile in
    return SKAction.run {
        let randomNum = arc4random_uniform(100)
        let randomTime = TimeInterval(randomNum / 10)
        let wait = SKAction.wait(forDuration: randomTime)
        let scale = SKAction.scale(by: 1, duration: 2)
        tile.sprite?.run(scale)
        maxDuration = max(maxDuration, randomTime + 2)
    }
}

// 2. create a wait action for the max duration
let wait = SKAction.wait(forDuration: maxDuration)

// 3. write inside this action the code to be executed after all the actions
let completion = SKAction.run {
    print("now all the actions are completed")
}
// 4. create a sequence of wait + completion
let sequence = SKAction.sequence([wait, completion])

// 5. create a group to run in parallel actions + sequence
let group = SKAction.group(actions + [sequence])

// 6. run the group on the node you prefer (it doesn't really matter which node since every inner action is tied to a specific node)
self.run(group)

更新（由@Alex 建议）

var maxDuration:TimeInterval = 0

tiles.forEach { tile in
    let randomNum = arc4random_uniform(100)
    let randomTime = TimeInterval(randomNum / 10)
    let wait = SKAction.wait(forDuration: randomTime)
    let scale = SKAction.scale(by: 1, duration: 2)
    tile.sprite?.run(scale)
    maxDuration = max(maxDuration, randomTime + 2)
}

run(.wait(forDuration: maxDuration)) {
    print("now all the actions are completed")
}