Swift - Using CGContext to draw with finger

Question

I\'m trying to make a drawing app. I have a single custom UIView:

class DrawView: UIView {

var touch : UITouch!
var lastPoint : CGPoint!
var currentPoint : CGPo         


        

Answer 1

Two things:

1. Calling self.setNeedsDisplay doesn't immediately call drawRect. It just sets a flag so that drawRect will be called in the near future. Since you set lastPoint to currentPoint right after that, when drawRect is called lastPoint is always equal to currentPoint.

2. drawRect redraws the entire view every time it is called, so at most you'd only ever see the most recent line. If you fixed problem 1, you'd have a short line following your finger instead of a dot. If you want to see the whole trail, you'll need to store the points in an array that is a property of your view, and then draw lines to connect all of the points in drawRect.