Structures

Model everyday objects using structures!

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Key Concepts

Review core concepts you need to learn to master this subject

Structure Creation

Default Property Values

Structure Instance Creation

Checking Type

init() Method

Structure Methods

Mutating Methods

Structure Creation

struct Building {
  var address: String
  var floors: Int

  init(address: String, floors: Int, color: String) {
    self.address = address
    self.floors = floors
  }
}

Structures, or structs, are used to programmatically represent a real-life object in code. Structures are created with the struct keyword followed by its name and then body containing its properties and methods.

Structures

Lesson 1 of 1

1
What is a Structure
As developers, we create programs and applications to solve problems — problems that we encounter on a daily basis that usually stem from everyday life. More often than not, these problems ar…
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2
Creating a Structure
With structures, we can create our own data type and use them to model everyday objects with their own unique characteristics. Here’s the basic syntax for a structure: struct Name { Properties }…
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3
Default Property Values
Now that we know how to create a structure we should also know how to create customized instances of that structure. But, what if we’re creating a lot of instances, do we really need to customize e…
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4
Creating an Instance
Instances are how we create individual objects using a structure. In the previous exercise’s example, we created a structure to model dogs: struct Dog { var age = 0 var isGood = true } In …
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5
Accessing and Editing Properties
We’ve created models of real-life objects using instances and now let’s find out how to customize them. Since instances of a struct can have different property values, we should know how to access …
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6
The Init Method
In the previous exercise, we’ve supplied our instances’ properties with default values. However, if we know that our struct instances vary a lot from one to another, we can include an init() method…
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7
Memberwise Initialization
In the previous exercise, we’ve explicitly provided an init() method inside our struct. Structures also come with a built-in memberwise initializer that can be used to assign values upon instance…
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8
Structure Methods
In addition to the init() method, we can also provide our structs with custom methods that instances can call. These instance methods are created like a normal function but within the scope of th…
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9
Mutating Methods
While a mutating method may sound like a term out of a mad scientist’s lab, it’s actually how we change an instance’s properties using an instance method. To do so, we need the mutating keyword: …
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10
New Type
In the previous exercises, we’ve done a lot with structures: we’ve created a structure, made instances, and added properties and methods, etc. So just take a second to pause and consider our achie…
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11
Structures are Value Types
In Swift, data types can be value types or reference types. This means that different data types are stored and accessed in different ways. Structures are value types, this means every time an …
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12
Review
Wonderful job, we’ve successfully created our own data type using structures and modeled dogs, books, and birds in our code! In this lesson, we covered: * Structures are a means of modeling real l…
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