Sprite Kit中的多点触控手势

Question

我正在使用XCode 6使用Sprite-Kit在Swift中工作,我有许多不同的节点,但目前我只设法检测一个手指并同时移动一个节点.我想知道如何能够检测多个手指以便同时移动多个节点.我的实际代码是:

var location = CGFloat() // finger position
var actualNode = -1 // node touched by the finger, -1 means no node touched

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) // when a finger touch the screen
{
    for touch: AnyObject in touches
    {
        location = touch.locationInNode(self) // we detect the finger position
    } 

    for var index = 0; index < colorNode.count; index++
    {
        if nodeAtPoint(location) == colorNode[index].node
        {
            actualNode = index // the number of the node touched by the finger
        }
    }
}

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) // when a finger move
{
    for touch: AnyObject in touches
    {
        location = touch.locationInNode(self) // we detect the finger position
    }

    if actualNode != -1 // if a node is touched
    {
        colorNode[actualNode].position = location // we move this node to the finger
    }
}
override func touchesEnded(touches: NSSet, withEvent event: UIEvent) // when a finger don't touch the screen anymore
{        
    actualNode = -1 // there is no node touched
}

你可以看到我只有position我的第一根手指,但我如何检测多个手指位置并将每个手指分配到手指触摸的节点？

Answer 1

同时移动多个节点非常简单.关键是要独立跟踪每个触摸事件.一种方法是维护一个字典,该字典使用触摸事件作为键,并将节点作为值移动.

首先,声明字典

var selectedNodes:[UITouch:SKSpriteNode] = [:]

将触摸事件作为键添加到字典中的每个精灵

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        let location = touch.location(in:self)
        if let node = self.atPoint(location) as? SKSpriteNode {
            // Assumes sprites are named "sprite"
            if (node.name == "sprite") {
                selectedNodes[touch] = node
            }
        }
    }
}

根据需要更新精灵的位置

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        let location = touch.location(in:self)
        // Update the position of the sprites
        if let node = selectedNodes[touch] {
            node.position = location
        }
    }
}

触摸结束时从字典中删除精灵

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        if selectedNodes[touch] != nil {
            selectedNodes[touch] = nil
        }
    }
}