How to move line with finger? - ios

Question

I am defining the following variables in my ViewController for a line.
var scanlineRect = CGRect.zero
var scanlineStartY: CGFloat = 0
var scanlineStopY: CGFloat = 0
var topBottomMargin: CGFloat = 30
var scanLine: UIView = UIView()
I can draw a line using UIView and can move it in vertical direction using UIView.animate method. How to move a line dragging it with finger?
func drawLine()
{
self.view.addSubview(scanLine)
scanLine.backgroundColor = UIColor.black
scanlineRect = CGRect(x: 15, y: 0, width: self.view.frame.width - 30, height: 5)
scanlineStartY = topBottomMargin
scanlineStopY = self.view.frame.height - topBottomMargin
scanLine.frame = scanlineRect
scanLine.center = CGPoint(x: scanLine.center.x, y: scanlineStartY)
scanLine.isHidden = false
}
func Move(Location : CGPoint)
{
scanLine.isHidden = false
weak var weakSelf = scanLine
UIView.animate(withDuration: 3.0, animations: {
weakSelf!.center = CGPoint(x: weakSelf!.center.x, y: Location.y)
}, completion: nil)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
{
var lastPoint = CGPoint.zero
if let touch = touches.first
{
lastPoint = touch.location(in: self.view)
}
Move(Location: lastPoint)
}
override func viewDidLoad()
{
super.viewDidLoad()
drawLine()
}

Answer 1

Try using touchesMoved instead of touchesBegan
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch = touches.first
guard let location = touch?.location(in: self.view) else{
return
}
scanLine.frame.origin = CGPoint(x: location.x-scanLine.frame.size.width/2, y: location.y-scanLine.frame.size.height/2)
}
updated
If you want only move in y axis only you need to change this line
scanLine.frame.origin = CGPoint(x: location.x-scanLine.frame.size.width/2, y: location.y-scanLine.frame.size.height/2)
use this instead note that scanline.frame.origin.x is unchanged
scanLine.frame.origin = CGPoint(x: scanLine.frame.origin.x, y: location.y-scanLine.frame.size.height/2)