1 00:00:01,740 --> 00:00:02,750 Hey What's up everybody. 2 00:00:02,750 --> 00:00:04,830 Mark Price here at deps slopes dot com. 3 00:00:04,830 --> 00:00:09,530 And today we are going to talk about classes in object oriented programming. 4 00:00:09,530 --> 00:00:16,440 And you may have heard these phrases before and now see how they actually work in real life. 5 00:00:16,470 --> 00:00:25,310 So we're going to create a new playground my playground we're going to call this one objects and classes. 6 00:00:27,140 --> 00:00:28,790 Let's put this over here in Iowa. 7 00:00:28,800 --> 00:00:35,910 Ten course in the swift section and create OK. 8 00:00:40,040 --> 00:00:41,960 Make it a little larger for you here. 9 00:00:45,590 --> 00:00:48,680 So what is a class. 10 00:00:48,680 --> 00:00:48,940 OK. 11 00:00:48,950 --> 00:00:52,870 So we've been working with classes and object oriented programming. 12 00:00:53,150 --> 00:00:58,970 I think some time since the 70s and before that was functional programming functional programming still 13 00:00:58,970 --> 00:01:00,380 exists today. 14 00:01:00,680 --> 00:01:06,740 But object oriented programming is probably the most popular form of programming currently and there 15 00:01:06,730 --> 00:01:10,910 are some new paradigms coming out that are trying to move away from it slightly like particle oriented 16 00:01:10,910 --> 00:01:16,460 programming which you also learn a little bit about of later on but object oriented programming is the 17 00:01:16,460 --> 00:01:22,910 idea where you can create a blueprint for something and create multiple copies of it. 18 00:01:22,910 --> 00:01:26,640 Perfect example is let's say a car in a car factory right. 19 00:01:26,720 --> 00:01:31,730 You can get a blueprint for a car and then create multiple copies of that car and say let's go ahead 20 00:01:31,730 --> 00:01:33,630 and use that example right here. 21 00:01:33,680 --> 00:01:36,740 We want to create a car so you create a class. 22 00:01:36,860 --> 00:01:38,040 OK. 23 00:01:38,480 --> 00:01:45,290 By defining the type the key word class and then the name of the class organise a car or better yet 24 00:01:45,290 --> 00:01:55,430 view a call OK and a vehicle has multiple properties and functions such as we say var a vehicle has 25 00:01:56,560 --> 00:01:58,220 a certain amount of tires. 26 00:01:58,400 --> 00:02:01,270 You can see it was 0 or 4. 27 00:02:01,450 --> 00:02:09,440 If it's a if it's a vehicle with four tires that could be a default value for instance a vehicle can 28 00:02:09,440 --> 00:02:12,490 have lights like headlight right. 29 00:02:12,500 --> 00:02:14,890 So how many headlights as a car have. 30 00:02:15,080 --> 00:02:24,720 You know what does the horsepower of a car you know or an ER vehicle 468 horsepower horsepower on a 31 00:02:24,720 --> 00:02:26,780 vehicle and a car can do things right. 32 00:02:26,820 --> 00:02:34,080 You can do things such as drives a function called Drive and it will you know there's some type of algorithm 33 00:02:34,080 --> 00:02:39,590 that will accelerate accelerate the vehicle you know. 34 00:02:39,690 --> 00:02:43,900 So a vehicle can drive a vehicle can break. 35 00:02:44,740 --> 00:02:51,280 OK so a class has properties such as tires headlights and horse power. 36 00:02:51,480 --> 00:02:54,470 And also can have functions such as drive and brake. 37 00:02:54,750 --> 00:03:00,180 And so what you want to do to understand object oriented programming is really visualize the world around 38 00:03:00,180 --> 00:03:00,420 you. 39 00:03:00,420 --> 00:03:05,040 Some people are really good at this like if you're an artist where you come from the design background 40 00:03:05,430 --> 00:03:09,890 object oriented programming tends to clean to you because you can do things like objects like people. 41 00:03:09,900 --> 00:03:14,080 Sometimes if you're more on the other side of the brain it's harder to visualize you're maybe think 42 00:03:14,090 --> 00:03:16,810 in numbers and things like that. 43 00:03:17,040 --> 00:03:22,620 Whereas this is very much a visual type of way of laying out your code. 44 00:03:22,620 --> 00:03:29,910 So when we're coding for instance or making an app like Instagram Instagram has users who can like other 45 00:03:29,910 --> 00:03:31,020 photos. 46 00:03:31,080 --> 00:03:37,710 So you might have a user object where it has the user id an account username and password as properties 47 00:03:38,010 --> 00:03:45,720 and it maybe has this user has functions such as you know reset password or delete account things like 48 00:03:45,720 --> 00:03:48,330 that and then even the pictures could be an object. 49 00:03:48,330 --> 00:03:53,580 A photo is an object so class photo and it has the selected filter. 50 00:03:53,760 --> 00:03:55,600 It has how many likes it has. 51 00:03:55,830 --> 00:03:57,400 How many comments it has. 52 00:03:57,450 --> 00:04:03,450 And those could be properties of it you know a photo you can add a function of a photo such as ADD like 53 00:04:03,930 --> 00:04:10,380 OK or remove like action items on it so you can start looking at objects and everything that's around 54 00:04:10,380 --> 00:04:11,760 you from the real world. 55 00:04:11,820 --> 00:04:13,230 Like oh there's a Bilgewater side. 56 00:04:13,230 --> 00:04:13,980 What does it have. 57 00:04:13,980 --> 00:04:15,330 Or there's a house. 58 00:04:15,330 --> 00:04:16,860 It has a door has windows. 59 00:04:16,860 --> 00:04:18,110 Those are the properties. 60 00:04:18,120 --> 00:04:23,500 What can a house do a house can cool down from the AC unit. 61 00:04:23,520 --> 00:04:28,680 So we can cool cool down house function or we can call heat up house function everything around you 62 00:04:28,950 --> 00:04:34,710 if you put it into some type of object can do something and also has properties of some crime or things 63 00:04:34,710 --> 00:04:35,730 that describe it. 64 00:04:35,730 --> 00:04:41,670 And so you're going to see a lot of objects in programming or a lot of classes and this is exactly how 65 00:04:41,670 --> 00:04:47,760 it works using the class cured and then giving it some type of name giving it properties and then functionality 66 00:04:47,760 --> 00:04:48,620 of some kind. 67 00:04:49,610 --> 00:04:54,710 Some of the classes that you'll see as you as you move along and programming and some now already worked 68 00:04:54,710 --> 00:05:02,780 with our you know things like this like view controllers like say class you know new VC VC for view 69 00:05:02,780 --> 00:05:06,410 controller and it has inherited from you I view controller. 70 00:05:06,620 --> 00:05:10,710 OK you've seen things like that and then you've seen the view did load. 71 00:05:10,810 --> 00:05:16,160 You've seen those functions there like that we've just created a class and we've inherited from another 72 00:05:16,160 --> 00:05:16,830 class. 73 00:05:16,870 --> 00:05:17,480 OK. 74 00:05:17,690 --> 00:05:18,470 Really cool stuff. 75 00:05:18,470 --> 00:05:24,410 And so to create an instance of your class or what we've done here is we've defined our class. 76 00:05:24,490 --> 00:05:26,390 But if we want to create an instance of it. 77 00:05:26,720 --> 00:05:27,090 OK. 78 00:05:27,110 --> 00:05:29,770 And let's give this view call a model. 79 00:05:29,780 --> 00:05:32,970 OK so VAR model OK. 80 00:05:33,230 --> 00:05:34,970 Just be a no model to begin with. 81 00:05:34,970 --> 00:05:43,310 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 82 00:05:44,330 --> 00:05:45,190 like so. 83 00:05:45,290 --> 00:05:53,550 And then you say BMW dot model equals the say 3:28 I. 84 00:05:53,990 --> 00:05:54,520 OK. 85 00:05:54,880 --> 00:05:58,100 And so you can set the properties of this class like so. 86 00:05:58,200 --> 00:06:04,070 But what's really cool is we can create as many as we want so I can say let them let's call this a Ford 87 00:06:04,280 --> 00:06:11,310 equals vehicle and we're going to say Ford model equals F-150. 88 00:06:11,420 --> 00:06:12,610 You see what's happening here. 89 00:06:12,680 --> 00:06:20,000 We created code one time but we can start creating multiple instances of that code and then setting 90 00:06:20,000 --> 00:06:26,060 the properties of it as well as calling the function such as I can say forward break and I've now called 91 00:06:26,060 --> 00:06:28,240 the function of this class. 92 00:06:28,430 --> 00:06:33,820 I've told it to do something and so propertys functions on a class. 93 00:06:33,820 --> 00:06:35,380 Think of it like a blueprint. 94 00:06:35,600 --> 00:06:38,440 When you're designing your apps you're designing anything. 95 00:06:38,620 --> 00:06:42,520 Think in your mind can I give this properties or attributes that describe it. 96 00:06:42,680 --> 00:06:45,520 And then think in your mind can it do anything. 97 00:06:45,530 --> 00:06:47,330 In most cases it's going to be yes. 98 00:06:47,440 --> 00:06:48,220 OK. 99 00:06:48,260 --> 00:06:52,190 Like if you had a bank account balance it's going to have your balance is going to have your first name 100 00:06:52,190 --> 00:06:57,710 your last name or your bank account and then it's going to have a function that says withdraw funds 101 00:06:57,710 --> 00:06:58,460 or add funds. 102 00:06:58,460 --> 00:07:05,600 There's going to be different things that can be happen to or that it can do in your class or in a bank 103 00:07:05,600 --> 00:07:12,590 account class for instance so classes they have properties they have functions things that can do stuff 104 00:07:12,950 --> 00:07:16,920 and then they have the ability to be instantiated. 105 00:07:16,930 --> 00:07:17,460 OK. 106 00:07:17,600 --> 00:07:22,760 At this point in time I am instantiating that the keyword instantiating an instance of the vehicle class 107 00:07:23,070 --> 00:07:26,120 I am instantiating another instance of the view class. 108 00:07:26,120 --> 00:07:27,980 These are also called objects. 109 00:07:28,070 --> 00:07:32,450 Once you've instantiated them they're called an object so you would say I have a foreign object or a 110 00:07:32,450 --> 00:07:36,010 BMW object or I'm creating an object or using an object. 111 00:07:36,170 --> 00:07:36,650 OK. 112 00:07:36,770 --> 00:07:40,230 At this point in time it's not an object it's just a class or a blueprint. 113 00:07:40,340 --> 00:07:45,370 But once it comes out of the factory OK when you instantiate it it becomes an object. 114 00:07:45,560 --> 00:07:46,220 OK. 115 00:07:46,250 --> 00:07:51,780 Another day another thing to know is that objects are passed by reference not by value. 116 00:07:51,980 --> 00:08:00,700 OK so when you let me show you here if I create a function and some function doesn't need to have a 117 00:08:01,160 --> 00:08:06,490 cool name and let's say we want to pass a bill here like so of type vehicle. 118 00:08:06,690 --> 00:08:07,680 OK. 119 00:08:08,780 --> 00:08:16,160 If I say View Haikal the model no. 120 00:08:16,190 --> 00:08:17,290 Now what I told you to do. 121 00:08:17,290 --> 00:08:21,020 I said lowercase I did not type in uppercase. 122 00:08:21,020 --> 00:08:24,180 It is really getting me here. 123 00:08:24,260 --> 00:08:28,450 View called Model equals cheese. 124 00:08:28,550 --> 00:08:29,470 OK. 125 00:08:30,140 --> 00:08:32,390 Something strange right. 126 00:08:32,450 --> 00:08:33,370 Get this. 127 00:08:33,380 --> 00:08:37,080 So let's say we have the Ford Model here right. 128 00:08:37,730 --> 00:08:42,340 And then I call some function and we know it says Ford F-150 because I put that in the model. 129 00:08:42,680 --> 00:08:51,050 So let's say let's print the Ford dot model so we're going to print it right here put on the right hand 130 00:08:51,050 --> 00:09:00,120 side that currently says F-150 But get this then I'm going to call some function and pass in Ford and 131 00:09:00,120 --> 00:09:05,770 then I'm going to print Ford model and look what happens. 132 00:09:05,770 --> 00:09:07,240 It's now cheese. 133 00:09:07,250 --> 00:09:09,890 Maybe you think to yourself wait what just happened. 134 00:09:09,910 --> 00:09:12,490 How is this being modified this is supposed to be a constant. 135 00:09:12,490 --> 00:09:15,250 You're not supposed to be able to modify this is what's going on. 136 00:09:15,250 --> 00:09:18,880 Well they're pass by reference OK an object has a reference in memory. 137 00:09:18,880 --> 00:09:22,270 You can't copy an object you cannot cannot copy an object. 138 00:09:22,280 --> 00:09:27,430 OK you can copy values like integers and doubles but you cannot copy an object so these are passed by 139 00:09:27,430 --> 00:09:29,820 reference a very important distinction. 140 00:09:29,830 --> 00:09:33,610 This gets a lot of bugs and new developers apps pass by reference. 141 00:09:33,620 --> 00:09:43,270 You write this down right here pass by reference K or there are reference objects and if you're still 142 00:09:43,270 --> 00:09:46,160 confused let's do the same example again. 143 00:09:46,200 --> 00:09:52,810 Let's say some function or actually let's just call this first one pass. 144 00:09:53,200 --> 00:09:55,770 We're passing an object by reference. 145 00:09:56,090 --> 00:09:58,780 So that's the name of this function now. 146 00:09:59,400 --> 00:10:05,080 OK let's get good new function here called pass by value. 147 00:10:05,080 --> 00:10:05,400 All right. 148 00:10:05,410 --> 00:10:16,910 And this takes a double or I'll say an integer is an integer let's say age K type int and let's say 149 00:10:16,930 --> 00:10:20,550 we say age equals 10. 150 00:10:20,560 --> 00:10:21,200 All right. 151 00:10:21,470 --> 00:10:23,220 I forgot the funk keyboard. 152 00:10:23,810 --> 00:10:27,040 OK so here we've modified our value. 153 00:10:27,190 --> 00:10:27,650 OK. 154 00:10:27,700 --> 00:10:29,950 Nothing was copied over. 155 00:10:30,130 --> 00:10:32,070 So we're going to do now. 156 00:10:33,130 --> 00:10:34,420 Well first off look at this. 157 00:10:34,450 --> 00:10:37,930 You can even change the value in because it's a constant. 158 00:10:37,930 --> 00:10:40,350 All right so that's already we can't do anything with that. 159 00:10:40,350 --> 00:10:51,670 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 pass 160 00:10:51,700 --> 00:10:55,360 in someone's age. 161 00:10:55,360 --> 00:11:02,220 It won't even work because these are constants so my point is when I pass this in here like this. 162 00:11:02,290 --> 00:11:02,840 OK. 163 00:11:02,950 --> 00:11:05,990 It's being copied in here like so. 164 00:11:06,640 --> 00:11:12,850 And then I can use the value here so I could say you know let new age equals H and this one will never 165 00:11:12,850 --> 00:11:13,740 be modified. 166 00:11:13,930 --> 00:11:14,320 OK. 167 00:11:14,350 --> 00:11:16,750 Never ever ever be modified. 168 00:11:16,810 --> 00:11:21,850 So important distinction pass by reference you can modify the object it points to a specific spot of 169 00:11:21,850 --> 00:11:28,900 memory value types like like the string or the double or the integer or float or Suji float things like 170 00:11:28,900 --> 00:11:31,230 that are all passed by value. 171 00:11:31,360 --> 00:11:32,830 Or rather they're copied over. 172 00:11:32,920 --> 00:11:39,030 OK one is copied one is not very important so this is the basics of classes and object oriented programming. 173 00:11:39,070 --> 00:11:44,380 You can create a class has properties that describe it and then it has actions that it can take or things 174 00:11:44,380 --> 00:11:47,080 that can act upon that object. 175 00:11:47,260 --> 00:11:50,800 It's going to take you some while a while to learn but as you do in this course and doing other things 176 00:11:50,800 --> 00:11:53,260 with programming it will all come together over time. 177 00:11:53,290 --> 00:11:54,160 But that's it for now. 178 00:11:54,160 --> 00:11:56,630 Mark Price of slopes dot com. 179 00:11:56,650 --> 00:11:57,720 See you soon.