ios - 捕获 swift 和 core 图形的要点

Question

我正在使用 swift 制作一个绘图应用程序

绘图应用程序的全部内容都是连接线，我在数组中存储了所有第一次触摸和最后一次触摸，所以我希望当用户在 View 中按下时，开始触摸将是距离数组更近的点:

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var drawingPlace: UIImageView!

    var startTouch : CGPoint?
    var finalTouch : CGPoint?
    var storePoints : [CGPoint] = [] // this will store the first touch and the last touch

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touch = touches.first
        let location = touch?.location(in: drawingPlace) //
        if startTouch == nil{
        startTouch = touch?.location(in: drawingPlace)
            storePoints.append(startTouch!)
        }else{
            for point in storePoints{

                if location == point { // i want to say if location == point or near the point
                    startTouch = point // so the start touch equal the point   
                }  
            }
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touch = touches.first
        finalTouch = touch?.location(in: drawingPlace)
        storePoints.append(finalTouch!)
        if startTouch != nil{
            UIGraphicsBeginImageContext(drawingPlace.frame.size)
            drawingPlace.image?.draw(in: drawingPlace.bounds)
            let context = UIGraphicsGetCurrentContext()

            context?.beginPath()
            context?.move(to: startTouch!)
            context?.addLine(to: finalTouch!)
            context?.strokePath()

            let img = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            drawingPlace.image = img

        }
    }

}

问题是:

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touch = touches.first
        let location = touch?.location(in: drawingPlace) //
        if startTouch == nil{
        startTouch = touch?.location(in: drawingPlace)
            storePoints.append(startTouch!)
        }else{
            for point in storePoints{

                if location == point { // i want to say if location == point or near the point
                    startTouch = point // so the start touch equal the point
                }
            }
        }
    }

我希望如果位置触摸位于 storePoints 数组的任何点周围，那么 startTouch 将等于该点。

任何想法我都会感激不尽。

马森

Answer 1

我不知道这是否是正确的方法，但它解决了 75% 的问题，代码:

func catchPoint(points : [CGPoint] , location : CGPoint){
        let qal = points[0].x - points[0].y
        for point in points{

            let x = location.x - point.x
            let y = location.y - point.y

            if abs(x) + abs(y) < abs(qal){
                startTouch = point
            }
        }
    }

为什么是 75%，因为:当数组有太多点时，它会变得更难捕获点仍然不知道为什么。

希望代码对某人有所帮助。