将 CGPoints 数组附加到数组：Array<Array<CGPoint>>?

Question

我有一个使用 Core Graphics 的绘图应用程序。一切正常。我会画画。我添加了一个“撤消”按钮来撤消该行。它有效，但是...

问题：每次按下“撤消”按钮时，它都会逐行删除。我正在尝试将 CGPath 数组附加到将保存整个图形的数​​组中。例如如果我从屏幕的左边缘到屏幕的右边缘画一条线，当我按下“UNDO”时，它应该删除这个“路径”（CGPoints 数组）。它目前正在逐行执行，这需要大约一百万次“UNDO”调用来删除相同的绘制路径。

可能的解决方案：我认为最好的方法是通过 touchesEnded 从 touchesBegans 收集 CGPoints 数组，然后将其附加到包含 CGPoints 数组的数组中。

 array<array<CGPoint>> //Using something like this

MainViewController：调用“UNDO”动作

 //calls the "undo" in UIView class
 @IBAction func undoButton(sender: AnyObject) {
 var theDrawView = drawView as DrawView
 theDrawView.undoLastPath()
}

自定义 UIView 类：

var lines: [Line] = []

var lastPoint: CGPoint!
var drawColor = UIColor.redColor()
var allLines = Array<Array<CGPoint>>()//Will store arrays of CGPoint Arrays


required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    var touch = touches.first as! UITouch
    lastPoint = touch.locationInView(self)
}

override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
    var touch = touches.first as! UITouch
    var newPoint = touch.locationInView(self)

    lines.append(Line(start: lastPoint, end: newPoint, color: drawColor))
    lastPoint = newPoint
    self.setNeedsDisplay()

}

override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
    var touch = touches.first as! UITouch
    var newPoint = touch.previousLocationInView(self)
    //ERROR: lines are not appending!
    allLines.append(lines(start: lastPoint, end: newPoint, color: drawColor))

    touchesMoved(touches, withEvent: event)
}

override func drawRect(rect: CGRect) {
    var context = UIGraphicsGetCurrentContext()
    CGContextBeginPath(context)
    CGContextSetLineWidth(context, 10.0)
    CGContextSetLineCap(context, kCGLineCapRound)

    //Currently this works: Will add the new allLines (Array)
    for line in lines {

        CGContextMoveToPoint(context, line.start.x, line.start.y)
        CGContextAddLineToPoint(context, line.end.x, line.end.y)

        //CGContextSetRGBStrokeColor(context, 0, 0, 0, 1.0)
        CGContextSetStrokeColorWithColor(context, line.color.CGColor)
        CGContextStrokePath(context)
    }
}
func eraseAll(){
    lines.removeAll(keepCapacity: false)
    self.setNeedsDisplay()
}

我的线的自定义 Swift 类：

class Line {
var start: CGPoint
var end: CGPoint
var color: UIColor
init(start _start: CGPoint, end _end: CGPoint, color: UIColor) {
    start = _start
    end = _end
    color = _color
    }
}

我尝试了多种不同的方法将行数组附加到 allLines 数组，但没有成功。

我怎样才能将我的线条画附加到这个：

 array<array<CGPoint>>

Answer 1

我相信你应该让你的allLines 成为Line 的数组：

var allLines = [[Line]]()

那么你的touchesEnded就变成了：

override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
    var touch = touches.first as! UITouch
    var newPoint = touch.previousLocationInView(self)
    lines.append(Line(start: lastPoint, end: newPoint, color: drawColor))
    allLines.append(lines)

    // Prep lines to hold the next line
    lines = []
}

在你的drawRect:

for lines in allLines {
    for line in lines {

        CGContextMoveToPoint(context, line.start.x, line.start.y)
        CGContextAddLineToPoint(context, line.end.x, line.end.y)

        //CGContextSetRGBStrokeColor(context, 0, 0, 0, 1.0)
        CGContextSetStrokeColorWithColor(context, line.color.CGColor)
        CGContextStrokePath(context)
    }
}

而undoLastPath 很简单：

func undoLastPath() {
    if count(allLines) > 0 {
        allLines.removeLast()
        self.setNeedsDisplay()
    }
}