iOS Swift 3 - Clearing the UIView - ios

Question

I'm building an iOS app where I have a class named "DrawableCanvas" that extends UIView. The idea is to enable users to draw on UIViews in the Storyboard that extend the class I made.
The drawing works fine and smooth at this point. Here's the code I used:
class DrawableView: UIView {
let path=UIBezierPath()
var previousPoint:CGPoint
var lineWidth:CGFloat=1.0
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override init(frame: CGRect) {
previousPoint=CGPoint.zero
super.init(frame: frame)
}
required init?(coder aDecoder: NSCoder) {
previousPoint=CGPoint.zero
super.init(coder: aDecoder)
let panGestureRecognizer=UIPanGestureRecognizer(target: self, action: #selector(pan))
panGestureRecognizer.maximumNumberOfTouches=1
self.addGestureRecognizer(panGestureRecognizer)
}
override func draw(_ rect: CGRect) {
// Drawing code
UIColor.black.setStroke()
path.stroke()
path.lineWidth=lineWidth
}
func pan(panGestureRecognizer:UIPanGestureRecognizer)->Void{
let currentPoint=panGestureRecognizer.location(in: self)
let midPoint=self.midPoint(p0: previousPoint, p1: currentPoint)
if panGestureRecognizer.state == .began{
path.move(to: currentPoint)
}
else if panGestureRecognizer.state == .changed{
path.addQuadCurve(to: midPoint,controlPoint: previousPoint)
}
previousPoint=currentPoint
self.setNeedsDisplay()
}
func midPoint(p0:CGPoint, p1:CGPoint)->CGPoint{
let x=(p0.x+p1.x)/2
let y=(p0.y+p1.y)/2
return CGPoint(x: x, y: y)
}
}
Of course, I have to clear the view on a button press, and here's my button press action:
#IBAction func reset1(_ sender: AnyObject) {
print("reset hit!")
sig1View.setNeedsLayout()
sig1View.setNeedsDisplay()
}
where sig1View is the view I'm trying to reset.
This didn't work out, so what I tried instead was to write a reloadData() in the DrawableView class:
func reloadData() {
print("reload data hit")
self.setNeedsDisplay()
}
The function got called, but that too, didn't work. How do I clear or reset a UIView in iOS Swift 3?

Answer 1

Call your DrawableView's (instance's) path.removeAllPoints function to remove all the drawings/path.
So following your code, reset1 should look like this now:
#IBAction func reset1(_ sender: AnyObject) {
print("reset hit!")
sig1View.path.removeAllPoints()
sig1View.setNeedsDisplay()
}

Answer 2

The problem is that, although your question talks about "resetting", your code does not in fact reset anything. You are saying:
override func draw(_ rect: CGRect) {
// Drawing code
UIColor.black.setStroke()
path.stroke()
path.lineWidth=lineWidth
}
So that's what's happening. As long as path contains a drawable path, that is what is drawn in your view whenever the view redraws itself. If that's not what you want, change the path, or change the implementation of draw.

Answer 3

Add this method to DrawableView class and call it with sig1View instance:
func clear()
{
path.removeAllPoints()
setNeedsDisplay()
}
and call it from the reset method.
Usage:
sig1View.clear()