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So in this lesson, all I'm gonna do is just a bit of tidy up around our codebase to make it a little
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bit shorter, a little bit more succinct, and a little bit easier to read.
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So the first thing I'm gonna do is I'm gonna get rid of our debug options, so for any app that you're
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putting on to the App Store, you probably don't want those dots confusing the user. And the next thing
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is I'm gonna get rid of all these comments and this bit of space. And then inside our touchesBegan where
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we create a new diceScene,
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I'm actually going to separate that out into its own function.
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I'm gonna call it addDice and it's going to take a single parameter which is going to be called 
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atLocation, and this is going to be of the type ARHitTestResults.
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Now, I'm going to take all of this code and put it into addDice. And then, over here, instead, I'm going
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to just going to call addDice atLocation which is the location that we got from our hitResult.
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And this is probably a good point to show you a different way of naming your methods in Swift.
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So, in Swift, there's something called the external parameter and the internal parameter. So we can say
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addDice atLocation which seems quite expressive when we call it.
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But when we want to use it inside our method, I don't really want to say atLocation.worldTransform.
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Just semantically or in English,
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that doesn't really sound good to me.
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So instead, I want to be able to write something like location.worldTransform.
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So I can keep the external parameter as atLocation, but I can change the internal parameter to simply location.
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So, now I can use location inside the method and still use atLocation outside the method to indicate
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what kind of input I'm looking for.
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And this is just a way of making your code more expressive so that somebody else who has never seen
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your code can have a look at it and be able to get to grips with it relatively quickly.
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All right.
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So we've separated that functionality out and I'm going to put this function above the rollAll.
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Now, this is really, really up to you,
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and this is completely personal, I would say. But I think it makes more sense hierarchically.
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I'm going to keep these three as they are, and then I'm going to move on to refactoring this didAdd
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delegate method.
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So one of the first things you can do is you can add a pragma mark to separate it out and we'll call this
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pragma //MARK: -  ARSCNViewDelegateMethods.
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And now, if you have a look in this dropdown, you can see we've got our categories,
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ARSCNViewDelegateMethods which has only one at the moment. But as your ARKit app gets more complicated,
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you're going to be putting more delegate methods in here and it'll be nice to be able to split them
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up. And equally, you could probably also split up the lifecycle methods up here,
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viewDidLoad, viewWillAppear, et cetera, and maybe your Dice Rendering Methods.
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Now, you can split this up however you like, but it's just nice when you can actually browse all your
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methods and properties and have some sort of structure that divides them up.
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So if you remember, by having that dash in there, you actually get a little line. If you don't have that
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dash, you only have this bit of text. And I quite liked that line separation, so I tend to have it in there.
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All right.
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So let's look at this renderer didAdd method, and one of the first things that you notice that is
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pretty long-winded are these lines here.
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If anchor is of the type ARPlaneAnchor, then let planeAnchor = anchor as! ARPlaneAnchor.
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So this, obviously, is there because I wanted this code to be as expressive as possible so that even a
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beginner could actually understand what the hell is going on.
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But now that we're refactoring, let's make this a little bit simpler.
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So first thing I'm gonna do is I'm actually going to take out all of that code, put it at the bottom
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and I'm going to comment it out.
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So right now we're not concerned with that.
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We just want to shorten all of this junk here.
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So instead of checking if anchor is off type ARPaneAnchor, and having an "else" statement that returns,
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we can actually get rid of all of these lines by simply using a "guard" statement. So I can say guard let 
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planeAnchor = anchor as? ARPlaneAnchor.
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And if the "guard" statement fails, then I'm simply going to return.
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So that single line of code has replaced all of this code and we can now get rid of it.
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But before I do that, I just want to show you how it works.
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So, firstly, let's look at this part.
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We're saying, "let," this new constant planeAnchor be set equal to anchor,
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and we're going to try and downcast it from ARAnchor type to ARPlaneAnchor type.
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Now, if this is not doable, i.e., the anchor that we actually detected was not of the type ARPlaneAnchor
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or cannot be converted into the type ARPlaneAnchor, then this planeAnchor is going to be an optional
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that's going to be equal to nil.
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And in that case, this fails. And then this guard statement will jump to the "else" portion in which case
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we return and we escape out of this entire function.
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So this is kind of like having a moat outside of your castle where you're tripping up all the things,
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you know, all the--all the cavalry, all the foot soldiers, and you're trying to prevent them from
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entering your main code, and you're just saying escape if this statement happens to trigger.
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So, now we can get rid of all of this and we can bring back all of our code down here.
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So the other thing I want to do is I actually want a separate method to create that plane.
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So I'm going to create another pragma mark down here and let's call it Plane Render Methods or Plane
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Rendering, I guess that makes more sense. And then I'm going to take all of this and I'm going to put
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it into a method here called createPlane with,
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and it takes a ARPlaneAnchor as a parameter and I'm going to paste it in here.
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So, again, I want to have with or withPlaneAnchor as the external name for this method. And the internal
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name,
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I'll just call it planeAnchor, so that we don't have to update our code too much.
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Okay. So, now we're going to call that method over here.
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We're going to say createPlane withPlaneAnchor and the anchor is, of course, this one.
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So let's pass that in there. And then I'm going to make sure that this method actually returns a
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SCNNode which is the one that I'm gonna be adding as the childNode.
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So I'm going to store this inside a constant called a planeNode.
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So planeNode equals the output of this function
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and, of course, we need to be able to return planeNode here for that to work.
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And then, finally, I'm gonna say node.addChildNode, and it's going to be playing node that we got
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back from that method. And all the errors disappear and all is well in the world.
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So you can probably even refactor this further.
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Another suggestion I would make is that this plane can actually be its own object.
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You can see that we're doing a lot of things on this plane, plane.position, planeNode, plane material,
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plane geometry.
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But for now, I'm happy with this. And I hope you enjoyed this bonus refactoring lesson and I like the way
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that our cleaner code looks. If you have any suggestions on future tutorials that you want us to make,
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then do go ahead and shoot me a message, and we're going to try and figure out what other things that
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most people want to learn about, and to use it to guide our future course development.
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So this is all from Angela at the London App Brewery and I hope you'll look forward to more tutorials that
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we're going to be adding to this course in the coming weeks and months.
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So thanks for watching this far, and see you soon.