How to move line? - ios

Question

How to move horizontal line in a vertical direction?
I can draw a straight horizontal line and I need to move it using long press.
How can I do that?
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
{
if let touch = touches.first
{
let currentPoint = touch.location(in: self.view)
DrawLine(FromPoint: currentPoint, toPoint: currentPoint)
}
}
func DrawLine(FromPoint: CGPoint, toPoint: CGPoint)
{
UIGraphicsBeginImageContext(self.view.frame.size)
imageView.image?.draw(in: CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height))
let context = UIGraphicsGetCurrentContext()
let lineWidth : CGFloat = 5
context?.move(to: CGPoint(x: FromPoint.x, y: FromPoint.y))
context?.addLine(to: CGPoint(x: FromPoint.x + 200, y: FromPoint.y))
context?.setBlendMode(CGBlendMode.normal)
context?.setLineCap(CGLineCap.round)
context?.setLineWidth(lineWidth)
context?.setStrokeColor(UIColor(red: 0, green: 0, blue: 0, alpha: 1.0).cgColor)
context?.strokePath()
imageView.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
}

Answer 1

you can draw a horizontal line using UIView and can move it in vertical direction using UIView.animate method by providing the required options.
In your ViewController define the following variables:
var scanlineRect = CGRect.zero
var scanlineStartY: CGFloat = 0
var scanlineStopY: CGFloat = 0
var topBottomMargin: CGFloat = 30
var scanLine: UIView = UIView()
Call drawLine method inside viewDidLoad method and call moveVertically method on your touch event:
func drawLine() {
self.addSubview(scanLine)
scanLine.backgroundColor = UIColor(red: 0.4, green: 0.8, blue: 0.4, alpha: 1.0) // green color
scanlineRect = CGRect(x: 0, y: 0, width: self.frame.width, height: 2)
scanlineStartY = topBottomMargin
scanlineStopY = self.frame.size.height - topBottomMargin
}
func moveVertically() {
scanLine.frame = scanlineRect
scanLine.center = CGPoint(x: scanLine.center.x, y: scanlineStartY)
scanLine.isHidden = false
weak var weakSelf = scanLine
UIView.animate(withDuration: 1.0, delay: 0.0, options: [.repeat, .autoreverse, .beginFromCurrentState], animations: {() -> Void in
weakSelf!.center = CGPoint(x: weakSelf!.center.x, y: scanlineStopY)
}, completion: nil)
}

Answer 2

what you can do is to draw this line on a UIView, and move the UIView upwards or to any position you want like so:
UIView.animate(withDuration: 0.3, animations: {
yourView.origin = CGPoint(yourView.frame.origin.x, yourYPosition)
}, completion: { (value: Bool) in
//do anything after animation is done
})