swift - 在 Swift 3 函数中同时运行代码块，然后等待完成

Question

我无法理解调度队列或任务处理程序在 swift 3 中如何工作。我的具体问题是:我遇到性能问题，想要并行运行多个代码块，并等待退出该函数，直到所有 block 都运行完毕完全的。我尝试简单地在后台异步运行这些 block ，但随后我得到“尝试在 xxx 发生变化时使用它”，因为我枚举了在异步队列上管理的相同数组或 enumerateChildNodes(...) 。我正在尝试管理最小化 SpriteKit 节点以提高 fps。以下是我想要并行运行并等待的代码块的示例:

  func determinePlatformNodesToUse() {

    // Code Block 1:
    for platform in platformArray {
        addPlatformNode(platform, leftDistance: leftDistance, rightDistance: rightDistance)
    }

    // Also part of Code Block 1:
    // resort the platform nodes to guarantee position sequence
    currentPlatformNodeArray.sort(by: { $0.position.x < $1.position.x })

    // Code Block 2:
    for character in characterArray {
        if character.type == CharacterType.Enemy {
            addCharacterNode(character, leftDistance: leftDistance, rightDistance: rightDistance)
        }
    }

    // Code block 3
    // put all the enemies into an array for update processing will be added in addCharacterNode
    currentMotionEnemyNodeArray.removeAll()

    // Also part of Code block 3
    foregroundNode.enumerateChildNodes(withName: CharacterType.Enemy.rawValue, using: {
        (node, stop) in
        if let enemy = node as? CharacterNode {
            if enemy.motionType != .Stand { // dont use .Stand as they dont have motion
                self.currentMotionEnemyNodeArray.append(enemy)
            }
        }
    })

    // Code Block 4
    for actionSceneObject in actionSceneObjectArray {
        addActionSceneObjectNode(actionSceneObject, leftDistance: leftDistance, rightDistance: rightDistance)
    }

    // At this point, wait until all blocks 1-4 above have finished

    // Run blocks 5 - 8 code in all in parallel

    // wait until blocks 5 - 8 have finished and then leave the function
  }

Answer 1

您可以使用NSOperation来实现您想要做的事情。可以通过以下方式完成:

func determinePlatformNodesToUse(completion: (_ success: Bool) -> Void) {

    let queue:OperationQueue = OperationQueue()
    queue.name = "com.SOQA.SOQA.name"
    queue.qualityOfService = QualityOfService.default
    queue.maxConcurrentOperationCount = 6

    let operation01:BlockOperation = BlockOperation { 
        // Code Block - 1
    }

    let operation02:BlockOperation = BlockOperation {
        // Code Block - 2
    }

    let operation03:BlockOperation = BlockOperation {
        // Code Block - 3
    }

    let operation04:BlockOperation = BlockOperation {
        // Code Block - 4
    }

    let operation05:BlockOperation = BlockOperation {
        // Code Block - 5
    }

    let operation06:BlockOperation = BlockOperation {
        // Code Block - 6
    }

    let operation07:BlockOperation = BlockOperation {
        // Code Block - 7
    }

    let operation08:BlockOperation = BlockOperation {
        // Code Block - 8
    }

    operation05.addDependency(operation01)
    operation05.addDependency(operation02)
    operation05.addDependency(operation03)
    operation05.addDependency(operation04)

    operation06.addDependency(operation01)
    operation06.addDependency(operation02)
    operation06.addDependency(operation03)
    operation06.addDependency(operation04)

    operation07.addDependency(operation01)
    operation07.addDependency(operation02)
    operation07.addDependency(operation03)
    operation07.addDependency(operation04)

    operation08.addDependency(operation01)
    operation08.addDependency(operation02)
    operation08.addDependency(operation03)
    operation08.addDependency(operation04)

    queue.addOperations([operation01, operation02, operation03, operation04, operation05, operation06, operation07, operation08], waitUntilFinished: true)
}

如果您对使用此示例有任何疑问，请随时发表评论。请随意提出修改建议以使其变得更好:)