Swift-如何在每个点可以具有单独颜色的位置上画一条线

Question

How is it possible in Swift to draw a line where each point can have a different color?

So let's say I have some data incoming which represents the color value of each dot in a line. How can I accomplish that? If I use UIBezierPath, I have a Path and I can only give the path a color. For my case, I have to make 600 Paths ( each dot a Path ) to get, what I would like to have.

Is there a simpler way?

Thank you very much!

EDIT: I've tried to create a 1x1 UIBezierPath and a CAShapeLayer for each. It works, but the whole app gets very very slow, so there must be a simpler or faster method, does anyone know a solution?

Answer 1

Now I am stuck here:

it actually works, as soon as I update my 2-D Array and my "start" property, it is redrawing the UIView, but that needs about 5 seconds. Does anyone know a faster method for doing this?

class CustomView: UIView {

public var context = UIGraphicsGetCurrentContext()

public var redvalues = [[CGFloat]](repeating: [CGFloat](repeating: 1.0, count: 500), count: 500)

public var start = 0
{
    didSet{
        self.setNeedsDisplay()
    }
}

override func draw(_ rect: CGRect
{
    super.draw(rect)
    context = UIGraphicsGetCurrentContext()
    for yindex in 0...499{
        for xindex in 0...499 {
            context?.setStrokeColor(UIColor(red: redvalues[xindex][yindex], green: 0.0, blue: 0.0, alpha: 1.0).cgColor)

            context?.setLineWidth(2)
            context?.beginPath()
            context?.move(to: CGPoint(x: CGFloat(xindex), y: CGFloat(yindex)))
            context?.addLine(to: CGPoint(x: CGFloat(xindex)+1.0, y: CGFloat(yindex)))
            context?.strokePath()
        }
    }
}
}

Answer 2

I don't think there's any way to draw the different legs of a bezier path with different settings. Individually drawing the lines is probably the way to go.