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Hey buddy what's going on this is Caleb with Deb's slopes dot com.

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And in this video we're going to be talking about variables.

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Now you're probably thinking wait variable's that's a really basic easy component of Swift I already

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know variables.

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Not like this you don't.

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In Arek Swift a variable is actually a custom version of a behavior subject which is a custom version

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of an observable so a variable in our X Swift can actually be used just like an ordinary variable.

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But of course you have the same subject functionality that you do with behavior subjects and published

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subjects but it works in a little bit different of a way.

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So that's why I'm going to show you.

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So go ahead and pull open your Rick's playground and we're going to go ahead and copy those three top

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lines that we've been using over and over again.

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And we're going to right click on behavior subject and create a new playground page.

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We're going to name it variable and then we're going to go ahead and select one of the numbered lines

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here.

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Select all and delete.

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Then go ahead and paste in your import our swift import playground support as well as the needs indefinite

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execution line.

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So that's cool but if you build it if you clean it let's clean it there.

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You might notice that it will say that it cannot access our X Swift.

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Let me go ahead and give it a shot here.

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Let me see if we actually do have access.

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OK.

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So observable is not showing up.

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That gives me a clue that we do not have it properly imported.

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I don't know if you see that that error message at the bottom is saying no such module.

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So let's fix that like we have before.

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I'm going to save this.

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Close it and reopen it.

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And as soon as it opens up we can go ahead and build it.

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And now we should have access to our observables.

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There we go.

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Cool cool.

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So that's just a really easy way to clean out the project and get it set up with swift.

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So we're going to create a variable which is a type of observable.

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Now go ahead and do that by typing var variable.

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Kind of redundant equals variable even more redundant.

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And we need to give it an explicit type.

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So using the brackets go ahead and pass string in so that it knows that it's of type string.

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Now a variable is just like a behavior subject in that it needs an initial value to begin.

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So think about it it's just like an ordinary variable if you're going to use a variable that has to

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have a value.

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So go ahead and pass in a string here saying hello.

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And now we have a variable observable that has a value of Hello.

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OK.

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Easy enough.

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Now what we're going to do to use it is different than behavior subjects and publish subjects a variable

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in and of itself does not register as an observable because it can be used in a couple of different

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ways.

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If we want to use our variable as an observable we need to tell our ex-wifes swift so.

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So go ahead and type variable dot as observable.

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Do you see that.

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And you know if we look at the description of this it says it's a canonical interface for push style

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sequence.

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That's not very clear but basically what you need to know is that this is going to convert our variable

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into a variable that is observable.

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OK.

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Otherwise it's just sort of like an ordinary variable you know what I actually I don't know if it's

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possible to do this let's try to just print the variable and see what happens if we printed out OK.

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So it shows up as a type or swift variable Swift got string.

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But I wonder if we were to pull out the value of that if it would print out.

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Hello.

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Okay.

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And it does so.

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Just so you know that's new to me as well.

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You can go into a variable and pull out its value.

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That's pretty cool.

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So anyway we have now cast our variable here as an observable.

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And next we're going to go ahead and try to subscribe to pull out the value.

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So go ahead and type.

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Dot subscribe and inside of Subscribe we're using on next just like we have in our previous videos with

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other subjects and I added some curly brackets there so that we have a closure that we're using the

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next closure.

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And basically we have already passed in a value we've already called on next once and so we can go ahead

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and we can print whatever that value is by using the dollar sign 0 K that's a temporary variable that's

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going to cycle through this whole sequence called variable and print out whatever is in there.

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And as you can see Hello Prince right out to the con..

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Pretty cool.

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So since this is a variable we can't pass in New values right.

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A variable can only have one value at a time.

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So if I try to go in and type variable dot on next doesn't work if I try variable as observable on next

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it doesn't work.

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OK.

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We cannot use this in the same way that we have been using other subjects and other observables.

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Think of a variable just like an ordinary variable.

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It's sort of like you're probably going to be most comfortable with variables.

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This type of variable with the capital V from our X Swift is going to feel a lot more natural to use

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if you're a non-reactive programmer which if you're taking this course I'm assuming you are we can use

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it just like an ordinary variable.

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All we need to do is call variable value and we can pull out the value that we want Ok that is variables.

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I mean honestly I wish that there was more I could tell you about but this is it.

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Variables are really simple and are swift just like they are in ordinary swift So this is Caleb with

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those slopes dot com and in the next video you're going to have a challenge.

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I'm going to challenge you to use your knowledge of subjects to build something really cool in code.

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So head over to the next video for your challenge.