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Hey What's up everybody.

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Mark Price here at the slopes dot com.

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And today we are going to talk about classes and object oriented programming.

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And you may have heard these phrases before and analyse how they actually work in real life.

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So we're going to create a new playground my playground we're going to call this one objects and classes.

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Let's put this over here in Iowa.

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Ten course in the swift section and create OK.

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It makes it a little larger for you here.

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So what is a class.

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OK.

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So we've been working with classes and object oriented programming.

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I think some time since the 70s and before that it was functional programming functional programming

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still exists today but object oriented programming is probably the most popular form of programming

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currently.

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And there are some new paradigms coming out that are trying to move away from it slightly like particle

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oriented programming which you also learn a little bit about of later on but object programming is the

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idea where you can create like a blueprint for something and create multiple copies of it.

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Perfect example is let's say a car and a car factory right.

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You can create a blueprint for a car and then you create multiple copies of that car.

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And so let's go ahead and use that example right here.

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We want to create a car so you create a class.

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OK.

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By defining the word type the key word class and then the name of the class organise say car or better

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yet view acle OK and a vehicle has multiple properties and functions such as we say var vehicle has

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a certain amount of tires.

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OK it's equal 0 or 4.

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If it's a if it's a vehicle with four tires that can be a default value for instance a vehicle can have

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lights like headlights right.

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So how many headlights as a car have.

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You know what is the horsepower of a car you know or an buccal 468 horsepower horse horsepower on a

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vehicle and a car can do things right you can do things such as drivers can create a function called

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Drive and it will you know there's some type of algorithm that will accelerate accelerate the UKL you

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know.

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So a vehicle can drive a vehicle can break.

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OK.

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So a class has properties such as tires headlights and horsepower and also can have functions such as

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drive and brake.

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And so what you want to do to understand object oriented programming is really visualize the world around

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you.

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Some people are really good at this like if you're an artist where you come from the design background

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object oriented programming tends to this clean to you because you can do things like objects like people.

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Sometimes if you're more on the other side of the brain it's harder to visualize you're maybe you think

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numbers and things like that.

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Whereas this is very much a visual type of way of laying out your code.

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So when we're coding for instance let's say we're making an app like Instagram.

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Instagram has users who can like other photos.

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So you might have a user object where it has a user ID an account username and password as properties

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and maybe has this user has functions such as you know reset password or delete account things like

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that.

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And then even the pictures could be an object.

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A photo is an object so class photo and it has the selected filter.

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It has how many likes it has how many comments it has.

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And those could be properties of it you know a photo you can at a function of a photo such as ADD like

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OK or remove like action items on it so you can start looking at objects and everything that's around

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you from the real world.

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Like others go outside.

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What does it have.

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Or there's a house.

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It has a door has windows.

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Those are the properties.

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What can a house do a house can cool down from the AC unit.

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So we can cool cool down house function or we can call heat up house function everything around you

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if you put it into some type of object can do something and also has properties of some time or things

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that describe it.

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And so you're going to see a lot of objects in programming or a lot of classes and this is exactly how

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it works using the class cured and then giving it some type of name giving it properties and then functionality

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of some kind.

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Some of the classes that you'll see as you as you move along and programming and some they've already

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worked with are you know things like this like view controller so I could say class you know new VC

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VC for view controller and it has inherited from you view controller OK.

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You've seen things like that and you've seen the view did load.

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You've seen those functions there like that we've just created a class and we've inherited from another

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class.

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OK.

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Really cool stuff.

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And so to create an instance of your class or what we've done here is we've defined our class.

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But if we want to create an instance of it.

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OK and let's give this vehicle a model case of our model so just be a no model to begin with.

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So what I can do is I can say let me say Let's call this BMW equals and then we'll create a new vehicle

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like so.

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And then we a BMW datt model equals the say 3:28.

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OK.

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And so you can set the properties of this class like so.

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But what's really cool is we can create as many as we want so I can say let Well let's call this a Ford

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equals vehicle and we're going to say Ford model equals F 150.

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You see what's happening here.

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We created code one time but we can start creating multiple instances of that code and then setting

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the properties of it as well as calling the function such as I can say for break and I've now called

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a function of this class.

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I'm told to do something.

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And so propertys functions on a class.

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Think of it like a blueprint.

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When you're designing your apps you're designing anything.

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Think in your mind can I give this properties or attributes that describe it and then think in your

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mind can it do anything.

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In most cases it's going to be yes.

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OK.

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Like if you had a bank account balance it's going to have your balance is going to have your first name

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your last name or your bank account and then it's going to have a function that says withdraw funds

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or add funds there's going to be different things that can happen to or that it can do in your class

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or in a bank account class for instance so classes they have properties they have functions things that

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can do stuff and then they have the ability to be instantiated.

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OK.

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At this point in time I'm instantiating that's the key word instantiating an instance of the vehicle

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class I am instantiating another instance of the vehicle class.

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These are also called objects.

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Once you've instantiated them they're called an object so you would say I have a foreign object or a

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BMW object or I'm creating an object or using an object.

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OK.

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At this point in time it's not an object it's just a class or a blueprint.

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But once it comes out of the factory OK when you instantiate it it becomes an object.

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OK.

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Another day another thing to know is that objects are passed by reference not by value.

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OK so when you let me show you here if I create a function and some function doesn't need to have an

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cool name and let's say we want to pass a viewpoint here like so of type buco.

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OK if I say View Hinkel the model no.

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Now what I told you to do I said lowercase I did not type in uppercase.

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It was really good me here.

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OK.

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View model equals cheese.

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OK.

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Something strange right.

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Get this.

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So let's say we have the Ford Model here right.

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And then I call some function and we know it's a Ford F-150 because I put that in the model.

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So let's say let's print the Ford dot model so we're going to print it right here.

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I'll put it on the right hand side that currently says F-150 150 but get this then I'm going to call

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some function and pass in Ford and then I'm going to print Ford model and look what happens.

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It's now cheese.

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Maybe you're thinking to yourself wait what just happened.

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How is this being modified this is supposed to be a constant.

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You're not supposed to be able to modify this is what's going on.

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Well they're pass by reference OK an object has a reference in memory.

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You can't copy an object you cannot cannot copy an object.

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OK you can copy values like integers and doubles but you cannot copy an object so these are passed by

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reference a very important distinction.

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This gets a lot of bugs and new developers apps pass by reference.

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You write this down right here pass by reference K or there are reference objects and if you're still

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confused let's do the same example again.

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Let's say some function are actually just this first one pass.

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We're passing an object by reference.

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So that's the name of this function now.

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OK let's get a new function here called pass by value.

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All right.

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And this takes a double or let's say an integer is an integer let's say age K type int and let's say

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we say age equals 10.

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All right.

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And I forgot the phunk cured.

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OK.

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So here we've modified our value.

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OK.

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Nothing was copied over.

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So we're going to do now.

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Well first off get this.

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You can even change the value in because it's a constant.

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All right so that's that's already we can't do anything with that.

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So if I was to say var someone's age equals 20 and then down here I was a call pass by value and I passed

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in someone's age.

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It won't even work because these are constants so my point is when I pass this in here like this.

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OK.

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It's being copied in here like so.

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And then I can use the value here so I could say you know let new age equals H and this one will never

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be modified.

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OK.

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Never ever ever be modified.

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So important distinction.

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Pass by reference you can modify the object it points to a specific spot of memory value types like

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like the string or the double or the integer or float or Suji float things like that are all passed

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by value.

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Or rather they're copied over.

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OK one is copied one is not very important so this is the basics of classes and object oriented programming.

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You can create a class has properties that describe it and then it has actions that it can take or things

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that can act upon that object.

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It's going to take you some while awhile to learn but as you do in this course and doing other things

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with programming it will all come together over time.

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But that's it for now.

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Mark Price of slopes dot com.

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See you soon.