Sprite Kit中是否有一种方法可以获取当前不动的手指坐标？

Question

为了避免意外的游戏行为，我想在任何给定时刻知道触摸屏上所有手指的坐标。 有办法吗？

例如，当从屏幕上移走第二个手指时，获取拳头的坐标。

提前致谢！

Answer 1

这是基于trojanfoe想法的解决方案。

import SpriteKit

class GameScene : SKScene {

struct fingerTrackData {
    var fingerID : Int // used to identify fingers in other part of the code
    var lastLocation : CGPoint // location of each finger
}

// array that stores information about each finger coordinates
var fingerTracks : [fingerTrackData] = []


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

    for touch in touches {

        let location = touch.locationInNode(self)

        // getAvailableFingerID() returns available fingerID to avoid ID duplication
        self.fingerTracks.append(fingerTrackData(fingerID: self.getAvailableFingerID(), lastLocation: location))

    }
}


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

    for touch in touches {

        let location = touch.locationInNode(self)

        self.updateFingerTracks(location)

    }

}


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

    for touch in touches {

        let location = touch.locationInNode(self)

        // deregistering unnecessary finger tracks
        self.fingerTracks.removeAtIndex(self.getClosestFingerArrayIndexByLocation(location))

    }
}


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

    // touchesCancelled occurs e.g. when more than 5 fingers on iPhone is on the screen

    // Deregistering all tracks here
    self.fingerTracks.removeAll()

}


override func update(currentTime: NSTimeInterval) {

    // to see in console what is actually happening in array
    if fingerTracks.count > 0 {

        for fingerTrack in self.fingerTracks {

            print("Finger: \(fingerTrack.fingerID) Location: \(fingerTrack.lastLocation)")
        }

    } else {

        print("---")

    }
}


/*
 * Below are some helper functions for convenience
 */

func getClosestFingerArrayIndexByLocation (location: CGPoint) -> Int {

    var fingerTrackKeyToUpdate : Int = 0
    var shortestDistance : CGFloat = 100500 // some big number that is much bigger than screen size

    for (fingerTrackKey, fingerTrack) in self.fingerTracks.enumerate() {

        // calculating distance from previous record for each finger
        let calculatedDistance = sqrt(pow(fingerTrack.lastLocation.x - location.x,2) + pow(fingerTrack.lastLocation.y - location.y,2))

        // shortest one gives us finger ID
        if calculatedDistance < shortestDistance {

            shortestDistance = calculatedDistance

            fingerTrackKeyToUpdate = fingerTrackKey
        }

    }

    return fingerTrackKeyToUpdate
}


func updateFingerTracks(location: CGPoint) {

    let closestFingerArrayIndex = self.getClosestFingerArrayIndexByLocation(location)
    let fingerIDToUpdate = self.fingerTracks[closestFingerArrayIndex].fingerID

    self.fingerTracks[closestFingerArrayIndex] = fingerTrackData(fingerID: fingerIDToUpdate, lastLocation: location)

}


func getClosestFingerIdByLocation(location: CGPoint) -> Int {

    return self.fingerTracks[self.getClosestFingerArrayIndexByLocation(location)].fingerID

}


func getAvailableFingerID() -> Int {

    var availableFingerID : Int = 0

    if self.fingerTracks.count > 0 {

        var checkAgain = true

        while checkAgain {

            checkAgain = false

            for fingerTrack in self.fingerTracks {
                if availableFingerID == fingerTrack.fingerID {
                    checkAgain = true
                    availableFingerID++
                }
            }
        }
    }

    return availableFingerID
}

}

Answer 2

谢谢大家的协助！

class GameScene : SKScene {

// stores all touches at any moment
var touchTracks : [UITouch] = []

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

    for touch in touches {

        self.touchTracks.append(touch)

    }
}


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

    for touch in touches {

        var touchIndexToRemove : Int?
        for i in 0..<self.touchTracks.count {

            if self.touchTracks[i] == touch {
                touchIndexToRemove = i
            }
        }
        self.touchTracks.removeAtIndex(touchIndexToRemove!)

    }
}


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

    // touchesCancelled occurs e.g. when more than 5 fingers on iPhone is on the screen
    // Deregistering all tracks here
    self.touchTracks.removeAll()

}

}