Swift Beginner: Classes and Structures

Transcript of the free preview lesson. Remaining lessons unlock with the full course.

Hello, my name is Mark Nair. And in these lessons, you'll learn about classes and structures, including making structures, instances, initializers, property observers, classes, and inheritance. Structures or structs, as what we say, are very common in Swift. We use them when we need to create an entirely new type of data structure for our work. I'm gonna quote the Swift programming language guide on this one, just to clarify it. To quote: "Structures are general-purpose, flexible constructs that become the building blocks of your program's code. You define properties and methods to add functionality to your structures and classes using the same syntax you use to define constants, variables, and functions." Well, that all sounds pretty good, but what does it mean? Well, let's take a look. I need a new type of information, new type of data for a bicycle. Now, early on, we would do something like this: "let bicycle =" And I'll just say, "Road bike." But that's all we have, there's nothing else about Road bike in here. If I wanted more information about Road bike, I could say Road bike. But it's just a string. So, the limitation here is it's a descriptor, a paragraph, words that describe Road bike, er, describe bicycle, but it doesn't let us do anything with it. A data structure does. So let's take bicycle and make this into a data structure. The way we do this is we begin with the keyword struct, which stands for structure. Now, I'm gonna make my struct called Bicycle. "Bicycle." Now, the way we do this is we capitalize the struct name right here. That's Bicycle. So the keyword struct, capitalize B for Bicycle. Then we add with the curly brace. Now, that's the skeletal view of a struct. So right now I have a struct called Bicycle. There's nothing in it. So let's give it some properties. Now, properties are things like this. I'll say "var name." And that is of type String. I don't have a name yet for the Bicycle. So I'm just going to set the placeholder of name without declaring the type. Like this. Swift will complain saying, "I don't know what to do about name. Name could be all sorts of stuff." That's why the error message is Type annotation missing in pattern there. Let's give it a type. It'll be a String. Let's make a brand. Let's give it some PSI for the tires. I'll make this a type of Int. Let's give it a weight. I'll make that a type of Double so we can have some 59.355 or something like that. 59 it's heavy. Okay. And let's give it a boolean value. Is it comfortable? It's looking pretty good. This is just the basic structure of a Bicycle. And the Bicycle now has these different properties, name, brand, tirePSI, weight, comfyRide, that we can then change, access, update, you name it. Now, how we're going to do that is by making an instance of this struct of Bicycle. Thanks for watching. In the next lesson, you'll learn about making instances of your struct.