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What's up everyone Mark Price here at Dev slopes dot com and let's continue building our arcade app

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here.

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And we want to do is get these items rotating and it may not be that complex actually and then maybe

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we'll do some refactoring.

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So first things first is how are we going to do it.

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Well we're going to need to just like you would use and spray it or seeing get where you need to use

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an action.

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And what we're going to do is create a rotate action sorgen say let rotate equals LCN action so a scene

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could action that repeat for ever and then we'll put an action set of here CN action that rotate by.

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We want to rotate by something OK and we are going to say 0 on the X but on the y.

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We're going to say C.G. flow because we're going to need to cast a value here 0.01 times double dot

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PI doubled up high as just pi.

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So it's the way you get pi you know 3.1 for blah blah.

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And then on the z axis we're going to rotate that either one is zero and the duration we're going to

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say 0.1.

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So every point of a second we want to rotate it by point 0 1 times double that PI along the along the

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y axis and then it will rotate it very smoothly.

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So long as we run the action forever.

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And so we've got the action here so what we can do now is here in our node we should just be able to

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add it to that so we're going to say no dot add action or run action is what I was looking for.

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Rotate and we're just going to copy this here and we're going to paste it here and we're going to paste

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it here.

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We're using the same action and rotating by the y axis.

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And let's see if that actually works for us here.

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And look at that we have rotating objects.

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Now we're going to leave this as is.

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But you could make this a little more exciting by having the rotating rotation star at a different time

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period so they're all rotating differently.

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They will be rotating at the same speed.

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That's important want to rotating at different speeds.

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But you might want to do delay the rotation on these by a couple of millisecond So they they are rotating

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at different angles or you could well you could also do which might even be better.

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Is rotate the object after you place it just rotate it at a certain position and then have it start

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there from that position and it would look cool or two but we're not going to answer that you can play

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with or with that you get the point.

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It's not a very hard thing to do and will be a challenge for you.

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So we've got two three objects here which is really awesome.

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So maybe the next thing to do is well think about this here we have these three objects here and I don't

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like the fact that the code we're copying and pasting the three times we may not be able to get around

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it but at least I think there could be a better place for that so we might want to refactor.

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But I think maybe instead what we can do is the tap detection whenever items tapped we just detect it

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and then we grab its name and pass it on to the previous view controller.

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So let's work on that feature now because we know that we're going to need it.

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So here we go.

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Stop it.

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Our computer runs nice and fast.

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And here in our ramp picker Visi let's just create the let's create a a gesture recognizer handler for

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when the screen is actually tapped and we'll add a just a tap gesture to the whole scene and then we'll

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handle it accordingly.

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So let's create a function here.

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When you say at 0 BJC because we're gonna use a gesture recognizer which is going to use the selector

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syntax we have to make this an object of C runtime function meaning it's going to use Objective-C features.

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When you say func handled tap and windows can say gesture recognizer you gesture recognizer and we're

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just putting the underscore here.

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So we don't have to give it a name and let's leave it empty for now.

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And then what we're going to do is actually add a gesture recognizer to the scene itself.

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So we'll do it right here.

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We'll say let tap equals you tap gesture recognizer and the target is going to be self and the action

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is going to be selector handle tap

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and then all we have to do is scene view not add gesture recognizer and let's add the taps.

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Now whenever somebody taps this screen or the scene.

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OK this scene kit scene.

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All we have to do.

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We're the scene view excuse me all we have to do is implement the code over here and handle tap.

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And what do we want to do.

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We want to detect which item was tapped.

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Or rather we want to even see if an item was tapped and if an item was tapped.

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What we want to do is get the name of that item and pass it back to the ramp.

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Placers So when you go to tap that screen and knows which ramp to to to place.

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OK.

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So let's get started.

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Let it kind of sound like Lego Batman.

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I should be in like Lego Batman 2.

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Let's write some code.

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I'm an orphan.

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Let p equals an orphaned coater gesture.

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Recognize in fact I should record my whole videos in a voice gesture recognizer that location.

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Now I'm feeling it.

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All right.

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Well when you're talking to yourself for hours on end at a screen pretending that people are there he

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will talk in a Batman voice to let the gesture recognize their location in view.

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And so which view do you want the scene view.

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So we want to detect the location of the tap in the scene view.

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So it's going to find the location.

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And it's going to store it here so we can use it and get results we're going to see if it actually hit

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something.

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OK.

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When I say scene view dot hit test and be very lucky that all of this code is written for us by Apple

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so we don't actually have to write.

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Great cast coded detection stuff.

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This makes it really easy.

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So we're going to pass and the point to see if something was hit and for the options we're going to

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go ahead and just put an empty dictionary here like so.

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OK.

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We don't need any options hit results.

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So we're going to see if anything was hit and if hit results count is greater than zero.

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So if we hit an object OK this would have a result greater than zero.

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We'd have one one or more object in our case we're looking for one.

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But what I'm saying is let's say we had five objects in the scene and we missed it.

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Where even are seem the three we missed it.

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This is going to be zero and we hit nothing.

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So we're going to see if anything was hit.

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OK.

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And if something was hit we're just going to grab the node that was hit we can grab it right here and

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this is how you would do with a game or air or anything when you're tapping the screen this is how you

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get a 3D object.

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And so you can reference it.

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And what we're going to do is we're going to say let Noad equals hit results zero note care where it

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is going to grab that node.

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No big deal.

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And then we're going to say switch.

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We're going to check now the name of the node.

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So switch node name and we're going to forcefully unwrap this.

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And the reason why we're going to forcefully unwrap it is because we're developing we're Sylhet compile

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time and the name of the node.

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OK.

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In our case we'll always be there.

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OK.

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And so at compile time we have to we have to force on wrap this here or we have to unwrap it here so

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we can know that it's there if it's not there or app won't even work.

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Now when would you not want to force and raptus OK.

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Well if you were let's say had a game and let's say the game had objects that were being deleted left

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and right like the lasers shooting aliens or something.

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OK.

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And then you went to go check the no name with a note and might not even be there could have been destroyed.

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Who knows that might not had a name at that point in time.

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And you could have a crash in that case you want to gracefully handle it with some some if let's regard

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statements.

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But in our case our app cannot function without this feature being there.

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So at compile time it will crash which is what we want we want it to crash.

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If it's if it's not there.

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So that's why I'm Force unwrapping it.

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So you because you'll hear me say don't ever force unwrap you know optionals because or Apple crash

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Well there are cases now you're becoming an advanced developer there are cases when it does not make

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sense to write a bunch of code for something that has to work no matter what and you understand more

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as time goes by as you program and switch.

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So we're just checking the name of the notes what we've done is we've tapped the screen.

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OK we've gotten the location story here in ppi.

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This is the point or the location that was tapped in the screen.

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And then what we do is we do a hit test when you pass a point into a hit test.

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It does all the math under the hood to see if you hit something and if it does OK the cap will be greater

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than zero.

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The hit results that count and then we grab the first element in there and we grab the note attached

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to it.

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There's other information attached with a hit but we're grabbing the node which so if we tapped the

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pyramid it would actually be grabbing the pyramid at this point in this node would be the pyramid.

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And then we're just checking the name.

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This is the identity that we set in the scene view when we looking at her objects.

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The node name.

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So I'm just doing a switch statement.

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Organise a case if the case is a pipe What do we want to do.

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Well we want to basically tell the other view controller that we selected the pipe.

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We don't have code for that yet.

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So we're just going to break and if the case is quarter let's say pyramid pyramid we're going to break

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in if the case is quarter we're going to break and then the default will just we'll just leave that

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empty for now.

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So this is looking good.

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It's yelling at us because we aren't doing anything here which is fine.

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But I want to we need to do now is have some way to let the other view controller know that we we selected

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something OK and that we we tap on something and then we want the other view controller to know that

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that's what we're going to do.

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We're going to grab that item and place it on the screen.

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And so there's two ways of doing this.

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We could do it with a protocol and become Adelia of the protocol.

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We could also hold a reference to the previous view controller as well.

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Either one would work just fine.

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And so let's just let's just keep it simple.

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First we can move to a protocol.

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We need to but let's just keep it simple and hold and hold a reference to the to the controller.

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So what I'm gonna do is appear at the top OK.

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We go we go back and fix this if we want a protocol's probably the best way going forward.

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But I think our app is simple enough where it doesn't need a protocol just yet.

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And I'm going to keep a weak more ramp place or VC ramp place or ABC and the reason I'm going to make

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it week is because we we don't want to retain cycle is probably not going to happen but we don't want

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one we don't want ramp or VC or executing ramp picker received a reference ramp place from Placer to

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reference this one with strong references because then we'll have retain cycle and have a memory leak.

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So we're making this week here.

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So rule of thumb if you don't understand this is if there are to view controllers referencing each other

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or to anything to if there are two objects ever referencing each other one of them needs to be weak

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or you will have a retain cycle possibly a memory leak which is which is no bueno.

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And if you need more information on it just do a research and research on iOS retain cycles and you

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can learn more about it.

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So ramp placer VC okay what we want to do is when we're loading when we're loading the this controller

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here we'll go ahead and set it.

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So what we'll do is here in our ramp place or TVC we will go find our pop over which is right here and

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then here's our ramp picker right and so what we can do is we can say ramp picker Visi ramp placer Visi

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equals self.

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Okay we're just sending in this view controller over here to the ramp ramp played for Durham picker

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and we're setting the ramp her or other ramp picker.

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If you're not confuse yet and so then what we do need to do is we need to have a function here that

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we call from the ramp picker.

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When an item is actually selected and I'm just going to call this function onramp selected and let's

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go ahead and just give it a rap name of type string.

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So on ramp selected.

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OK.

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So that's good.

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Let's just give it a let's give it an empty name there onramp selected.

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What do you want to do.

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Well that doesn't matter just yet.

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We just want to implement the function here so cool again if you're going to be doing a lot of back

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and forth between if you control you're going to want as a protocol we're just doing one function here

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so I'm not overly concerned about it.

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And you can always refactor.

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So rap picker visi.

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So what we're doing is in every single one of these here we're just going to pass in the name of the

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item that was selected so we can work with it.

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So it should be as simple as doing something like this ramp placer Visi dot on ramp selected or passing

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the pipe and just literally do the same thing for each one just with a different object in there so

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cramped place or VCDs up on ramp selected.

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And we're going to pass in the name.

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We're going to pass and pipe pyramid

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and then the quarter pipe.

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You know I'm wondering if we even need to do this at all on ramps like that we just pass and if we just

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pass in the name without even doing a switch statement that would be weightless code so we could technically

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just say ramp place or AVC on ramp selected and let's just passing the node name and get rid of all

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this code that we just wrote make it mo better.

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Yeah that'll work.

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And since we don't have anything else in the scene we only have three objects.

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We know it's only going be one of three names.

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And so I feel good I feel okay doing this putting this in here.

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And so yeah if there's is yeah we got a note here this is great.

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I think this will work just fine.

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So we'll see if something's been tapped and if it's been tapped we just pass in the name of the object

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which will go over here to our ramp placer and then we can do what we want with it which is technically

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grabbing building that object again and then putting on the scene and maybe you think it will mark why

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don't we just pass the whole note over to the ramp placer and use the same used the same object.

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Well we could but you know we've got an action running on a rotate action and we also the scale and

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the position are going to be off because it's different on the screen we need it full size now and I

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think it's cleaner to just recreate a new one.

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So I think this is great.

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We've got here is we've got a function that when we tap it it works well does when it works actually

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let's test it here.

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Let's let's go ahead and just print and we're going to say no name and see if it actually works.

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How about that.

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Then we'll know if it's actually working.

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OK.

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The secret button.

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So they're definitely spinning.

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So when I click these we should see names print out OK.

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There it is.

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Pipe pyramid quarter quarter quarter pyramid pipe.

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So it's definitely working.

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Our code is working.

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Look how easy it is to do hit detection with the scene.

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Apple did all the hard work for us under the hood and we just had to implement the code here.

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So really good stuff let's call this video done.

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And in the next exciting video what we'll do is we'll make it so when you select this it dismisses the

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view controller goes back to the other scene and then lets us place an object on the other scene.

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So that's it for now.

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Mark Price at death slopes Delcam moving on forward.