multithreading - 如何在不同线程上运行函数？

Question

我需要下面的函数在不同的线程上运行。我想我必须使用并发调度队列，但我不知道如何做到这一点，所以我希望得到一些帮助!

第一个函数:

func respondToSwipeGesture(sender: UISwipeGestureRecognizer) {

            switch sender.direction {
        case UISwipeGestureRecognizerDirection.Left:
            if self.imageView.tag == 1 {
                println("1 point!")
            } else {
                if self.imageView.tag == 5 {
                    println("1 point!")
                } else {
                    println("Game Over!")
                }
            }
        case UISwipeGestureRecognizerDirection.Down:
            if self.imageView.tag == 2 {
                println("1 point!")
            } else {
                if self.imageView.tag == 8 {
                    println("1 point!")
                } else {
                    println("Game Over!")
                }
            }
        case UISwipeGestureRecognizerDirection.Right:
            if self.imageView.tag == 3 {
                println("1 point!")
            } else {
                if self.imageView.tag == 7 {
                    println("1 point!")
                } else {
                    println("Game Over!")
                }
            }
        case UISwipeGestureRecognizerDirection.Up:
            if self.imageView.tag == 4 {
                println("1 point!")
            } else {
                if self.imageView.tag == 6 {
                    println("1 point!")
                } else {
                    println("Game Over!")
                }
            }
        default:
            break
        }

第二个函数:

 @IBAction func handleAttachmentGesture(sender: UIPanGestureRecognizer) {
    let location = sender.locationInView(self.view)
    let boxLocation = sender.locationInView(self.imageView)

    switch sender.state {
    case .Began:
      println("Your touch start position is \(location)")
      println("Start location in image is \(boxLocation)")

      // 1
      animator.removeAllBehaviors()

      // 2
      let centerOffset = UIOffset(horizontal: boxLocation.x - imageView.bounds.midX,
        vertical: boxLocation.y - imageView.bounds.midY)
      attachmentBehavior = UIAttachmentBehavior(item: imageView,
        offsetFromCenter: centerOffset, attachedToAnchor: location)

      // 3
      redSquare.center = attachmentBehavior.anchorPoint
      blueSquare.center = location

      // 4
      animator.addBehavior(attachmentBehavior)

    case .Ended:
      println("Your touch end position is \(location)")
      println("End location in image is \(boxLocation)")

      animator.removeAllBehaviors()

      // 1
      let velocity = sender.velocityInView(view)
      let magnitude = sqrt((velocity.x * velocity.x) + (velocity.y * velocity.y))

      if magnitude > ThrowingThreshold {
        // 2
        let pushBehavior = UIPushBehavior(items: [imageView], mode: .Instantaneous)
        pushBehavior.pushDirection = CGVector(dx: velocity.x / 10, dy: velocity.y / 10)
        pushBehavior.magnitude = magnitude / ThrowingVelocityPadding

        self.pushBehavior = pushBehavior
        animator.addBehavior(pushBehavior)

        // 3
        let angle = Int(arc4random_uniform(20)) - 10

        itemBehavior = UIDynamicItemBehavior(items: [imageView])
        itemBehavior.friction = 0.2
        itemBehavior.allowsRotation = true
        itemBehavior.addAngularVelocity(CGFloat(angle), forItem: imageView)
        animator.addBehavior(itemBehavior)

        // 4
        let timeOffset = Int64(0.4 * Double(NSEC_PER_SEC))
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, timeOffset), dispatch_get_main_queue()) {
            self.resetDemo()
        }
      } else {
        resetDemo()
        }

    default:
        attachmentBehavior.anchorPoint = sender.locationInView(view)
        redSquare.center = attachmentBehavior.anchorPoint
    }

Answer 1

不确定您要做什么(尚未阅读完整代码)。但是，如果您确定需要在不同的队列上运行，这里有一个可能对您有帮助的简单示例:

let aCustomQueue = dispatch_queue_create("aCustomQueueLabel", DISPATCH_QUEUE_CONCURRENT)
let anotherCustomQueue = dispatch_queue_create("anotherCustomQueueLabel", DISPATCH_QUEUE_CONCURRENT)

dispatch_async(aCustomQueue) {

    for _ in 0...1000 {
        NSLog("Hello") // println("Hello") will print char by char
    }
}


dispatch_async(anotherCustomQueue) {

    for _ in 0...1000 {
        NSLog("World") // println("World") will print char by char
    }

}

否则，您可能想看看:

• 中央调度 (GCD) 引用:https://developer.apple.com/library/prerelease/ios/documentation/Performance/Reference/GCD_libdispatch_Ref/index.html#//apple_ref/c/func/dispatch_get_main_queue
• 雷·文德利希 (Ray Wenderlich) GCD:http://www.raywenderlich.com/79149/grand-central-dispatch-tutorial-swift-part-1