PaintCode animation in Xcode

Question

I am trying to understand how PaintCode animations can be intergated in Xcode. In my example I have a ball going from right to left. I want the animation to start as long as the app starts and stop when you stop the stop button. In the attachments is what i have done so far:

When I run it returns an error:

Answer 1

A few things are wrong here

• First thing that is wrong is that your drawBall function is defined with an argument, but you never pass anything to it through the NSTimer. You should use the userInfo argument of the NSTimer initialisation if you want to pass an argument to the timer fire function.

• Second of all, your NSTimer is trying to call the selector "drawBall", but your function is defined with an argument. Therefore it should be "drawBall:".

• Third of all, I'm pretty sure the external argument name in your function is interfering with the selector name.

Try changing it to:

func drawBall(var fraction:CGFloat) {

...

}

It's also worth noting that you can define selectors in swift just by using the string literal syntax. Therefore you could just provide "drawBall:" in your NSTimer.

Furthermore, there are a few other things that you'll want to look into...

• You never pass the fraction variable into your drawRect method
• You never invoke your drawRect method (do this though using setNeedsDisplay())