Hi guys, 
I’m new in iOS development and have some questions about basics and Core Graphics. 

First I’ve understood that each ViewController has his own class which is like the brain of the ViewController. And I can also give the View its own class.

In the core graphics video he gave the View a class named „Draw Examples“ and wrote the following code: 

class DrawExamples: UIView {

    override func drawRect(rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()
        CGContextSetLineWidth(context, 3.5)
        CGContextSetStrokeColorWithColor(context, UIColor.blackColor().CGColor)
        CGContextMoveToPoint(context, 50.0, 60.0)
        CGContextAddLineToPoint(context, 200.0, 200.0)

But why is this line drawn after the start? Were is this method called? Because I only overwrote this method but did not call it. 
And how can i draw a circle in the „touchesBegan“-Methode?