How to start function drawRect(rect: CGRect) ? Swift

Question

I have rect:CGRect function inside my app, how can i use it ? I try

  drawRect(CGRect,x1:33.33,y1:23.45)

but doesn't work my function under below.

func drawRect(rect: CGRect,x1: CGFloat, y1: CGFloat) {

let center = CGPoint(x:x1/2, y: y1/2)
let radius: CGFloat = max(bounds.width, bounds.height)
let arcWidth: CGFloat = 100
let startAngle: CGFloat = 3 * π / 5.99
let endAngle: CGFloat = π / 1.40

let path = UIBezierPath(arcCenter: center,
                        radius: radius/2 - arcWidth/2,
                        startAngle: startAngle,
                        endAngle: endAngle,
                        clockwise: true)


path.lineWidth = arcWidth
counterColor.setStroke()
path.stroke()


}

better to call `setNeedsDisplay` which can call `drawRect` itself for your view. Ultimately `drawRect` is called by itself whenever a view of its type is initialized — Rajan Maheshwari, Oct 11 '16 at 18:04
What doesn't work? That's **not** the `drawRect` method called by `setNeedsDisplay` or similar. — vadian, Oct 11 '16 at 18:04
What is this custom `drawRect` method you have? It's not the right one from `UIView`. — rmaddy, Oct 11 '16 at 18:05
ohh yes.. That is something different and not the one from `UIView` — Rajan Maheshwari, Oct 11 '16 at 18:10
You better rename your methode to get better answers and not frighten the friendly iOS reader. I supect you want to draw somthing which you can see on screen. In this case this answer might help: http://stackoverflow.com/a/21312119/1457385 — shallowThought, Oct 11 '16 at 18:22

score 2 · Accepted Answer · answered Oct 11 '16 at 18:03

2

You never call drawRect yourself. It's called by the framework when needed.

The proper solution is to call setNeedsDisplay() on the view. Call this whenever the state of the view changes such that you want drawRect to be called.

On top of this, you have the wrong drawRect method. The one from UIView only has one parameter - the CGRect.

And in Swift 3 it would be:

override func draw(_ rect: CGRect) {
}

answered Oct 11 '16 at 18:03

rmaddy

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dude yeah worked fine but how can i add parameters in function x1, y1 like ? – SwiftDeveloper Oct 11 '16 at 18:09
and i want to use it without override ? which changes i need to do ? – SwiftDeveloper Oct 11 '16 at 18:11
1

You can't change the signature of the method. You need to use properties. Then anytime the values of these properties changes, call `setNeedsDisplay()`. And be sure your `draw` method uses the properties. – rmaddy Oct 11 '16 at 18:11
can you show setNeedsDisplay() sample codes changes inside my codes here ? inside your answer TY – SwiftDeveloper Oct 11 '16 at 18:11
1

That's it, just call `setNeedsDisplay()`. – rmaddy Oct 11 '16 at 18:12

score 1 · Answer 2 · answered Oct 11 '16 at 18:04

1

You should not call drawRect(). When you want to view to redraw, call the setNeedsDisplay() method.

answered Oct 11 '16 at 18:04

TheAppMentor

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1

The OP has a bigger problem - they have not implemented the proper `drawRect` method. – rmaddy Oct 11 '16 at 18:05
1

`setNeedsDisplay` will not call **that** particular method. – vadian Oct 11 '16 at 18:06
1

oops my bad. Did not realize its a custom drawRect method. Not sure if its a good idea to call a custom method drawRect too. – TheAppMentor Oct 11 '16 at 18:07

How to start function drawRect(rect: CGRect) ? Swift

2 Answers2