Intro to iOS Development
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    • 🍼A1: Swift Basics
    • 🧑A2: Profile
    • 💬A3: ChatDev
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    • 👨‍🍳A4: ChefOS - SwiftUI
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  • Lectures
    • 1️⃣Logistics + Swift Basics
    • 2️⃣UIKit + AutoLayout
  • 3️⃣MVC + Navigation + Delegation
  • 4️⃣UITableView
  • 5️⃣UICollectionView
  • 6️⃣Networking I
  • 7️⃣Networking II
  • 8️⃣SwiftUI I
  • 9️⃣SwiftUI II
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  • 🔔(11) Notifications
  • 🌎(12) Deployment and MapKit
  • Chapters
    • 🖐️Introduction
    • ☁️Git + GitHub
      • 1️⃣Git Installation
      • 2️⃣Git Basics
      • ➕Git+
    • 🐣Swift Basics
      • 1️⃣Variables and Constants
      • 2️⃣Data Types
      • 3️⃣Operators
      • 4️⃣Data Structures
      • 5️⃣Conditionals
      • 6️⃣Loops
      • 7️⃣Functions
      • 8️⃣Closures
      • 9️⃣Optionals
    • 🧰UIKit + AutoLayout
      • 1️⃣Classes
      • 2️⃣UIKit
      • 3️⃣AutoLayout
    • 📺MVC + Navigation + Delegation
      • 1️⃣MVC
      • 2️⃣Navigation
      • 3️⃣Delegation
    • 🏓UITableView
      • 1️⃣What is a UITableView?
      • 2️⃣UITableView Setup
    • 📚UICollectionView
      • 1️⃣What is a UICollectionView?
      • 2️⃣UICollectionView Setup
    • 🌐Networking I
      • 1️⃣HTTP Requests
      • 2️⃣Callbacks
      • 3️⃣Codable
    • 🌍Networking II
      • 1️⃣Alamofire
      • 2️⃣GET Requests
      • 3️⃣POST Requests
      • 4️⃣URLSession
    • 💾Persistence + SnapKit
      • 1️⃣Persistence
      • 2️⃣SnapKit
    • 🕊️SwiftUI
      • 1️⃣Introduction to SwiftUI
      • 2️⃣Getting Started with SwiftUI
      • 3️⃣Views + Modifiers
      • 4️⃣Layouts
      • 5️⃣Navigation
      • 6️⃣Property Wrappers
    • 🎛️Widgets
      • 1️⃣Introduction to Widgets
      • 2️⃣Setting Up Widgets
      • 3️⃣Building Widgets
      • 4️⃣Configuring Widgets
    • 🧱Project Foundation
    • ✅Testing
      • 1️⃣Unit Testing
    • 👣Debugging
      • 1️⃣OSLog
      • 2️⃣Crashlytics
      • 3️⃣Analytics
    • ☁️CI/CD
      • 1️⃣Xcode Cloud
      • 2️⃣AppStore Shipping
  • Guides
    • 🔨Xcode Project Setup
    • 🎨Figma
    • 📬Postman
    • 🥥CocoaPods
    • 🧰UIKit Handbook
    • 📑Tab Views
      • UITabBarController
      • TabView
  • Work in progress
    • 🧵Concurrency
    • 2️⃣UI Testing
    • 🕐Reactive Programming
    • 🧠Memory Management
      • 🔁ARC
    • 📦Storage
    • 📣Notifications
  • Archived
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        • 🗓️Schedule
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      • Assignments
        • 🍼A1: Swift Basics
        • 🧑A2: Profile
        • 💬A3: ChatDev
        • 👨‍🍳A4: ChefOS
        • 📱Hack Challenge
          • 🏆FA23 Winners
      • Lecture
        • 0️⃣Course Intro + Logistics + Git Setup
        • 1️⃣Swift Basics
        • 2️⃣UIKit + AutoLayout
        • 3️⃣MVC + Navigation + Delegation
        • 4️⃣UITableView
        • 5️⃣UICollectionView
        • 6️⃣Networking I
        • 7️⃣Networking II
        • 8️⃣Persistence + SnapKit
        • 🔟SwiftUI
        • 🔢TabViews
    • FA23
      • Logistics
        • 🐣Getting Started
        • 🐦Course Staff
        • 📜Syllabus
        • 🗓️Schedule
        • 🖊️Grading
        • 🙋‍♂️Office Hours
      • Assignments
        • 🍼A1: Swift Basics
        • 🧑A2: Profile
        • 💬A3: ChatDev
        • 👨‍🍳A4: ChefOS
        • 📱Hack Challenge
          • 🏆FA23 Winners
      • Lectures
        • 0️⃣Course Intro + Logistics
        • 1️⃣Swift Basics
        • 2️⃣UIKit + AutoLayout
        • 3️⃣MVC + Navigation + Delegation
        • 4️⃣UITableView
        • 5️⃣UICollectionView
        • 6️⃣Networking I
        • 7️⃣Networking II
        • 8️⃣Persistence + SnapKit
        • 🎛️Widgets
          • 👼Introduction to Widgets
          • ⚒️Setting Up Widgets
          • 🧱Building Widgets
          • 👨‍💻Configuring Widgets
        • 🔟SwiftUI
    • SP23
      • Logistics
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        • Syllabus
        • Grading
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      • Chapters
        • 1. Intro to Swift & Xcode
          • Lecture Handout
          • Lecture Demo
          • 🍼Project: Swift Basics
        • 2. UIKit and AutoLayout
          • Lecture Handout
          • Lecture Demo
          • 🛒Project: UIKit + AutoLayout
        • 3. Navigation, MVC, and Delegation
          • Lecture Handout
          • Lecture Demo
          • Project: Navigation + Delegation
        • 4. UITableView
          • Lecture Handout
          • Lecture Demo
          • Project: UITableView
        • 5. UICollectionView
          • Lecture Handout
          • Lecture Demo
          • Project: UICollectionView
        • 6. Networking I
          • Lecture Handout
          • Lecture Demo
          • Project: Persistence
        • 7. Networking II
          • Lecture Handout
          • Lecture Demo
            • Message Board
          • Project: Networking II
        • 8. Swift UI
        • 9. CocoaPods
          • 🍫Lecture Handout
          • 🧑‍🍳Lecture Demo
      • Cheat Sheets
        • Setting Up a New Xcode Project
        • Submitting Your Projects
        • Setting Up CocoaPods
    • 2022
      • SwiftUI
    • 2021
      • Adding Flare
      • Project: UIView Animations (Optional - Extra Credit)
      • UIView Animations
      • Xcode Tips and Tricks
    • 2019
      • Firebase
      • Persistence: UserDefaults
  • Swift Guide (ARCHIVED)
    • About this Textbook
    • Documentation
    • Constants and Variables
      • Variable Properties
      • Lazy and Static Variables
    • Functions
    • Ranges
    • Arrays
      • Basic Array Operations
      • Iteration and Enumeration
      • Advanced Array Operations
    • Tuples
    • Conditions and While Loops
    • For Loops
    • Enums and Switches
      • Enums with Associated Values
      • Indirect Enums
    • Classes and Structs
    • Optionals
    • Dictionaries
      • Dictionary Implementation
    • Closures
    • Constraints
    • Generics
    • Protocols
      • Protocols With Associated Types
    • Casting
    • Errors
    • Networking
      • Result
    • Inout
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  1. Chapters
  2. Swift Basics

Data Structures

Fall 2023 | Vin Bui

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Last updated 1 year ago

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We learned how to use variables and constants to store data, but only explored basic values such as integer numbers and text. However, when we program, we often need to hold more complicated data that requires a specialized format for organizing and retrieving the data. To do this, we use Data Structures.

Arrays

The most common data structure that we will be using is an array. Arrays store a group of values together into a single collection, and we can access these values using their position in the array.

var staff = ["Vin", "Richie", "Tiffany", "Jennifer", "Antoinette", "Elvis"]
staff[0]
staff[1]
staff[2]

We use square brackets [] to mark the start and end point of the array and use commas , to separate each value.

Swift uses type inferencing to determine the type of staff. Because all of the elements inside of the array are strings, Swift knows that staff is an array of strings (Array<String>). If we change the value of an element to a different type, our code will not compile.

Instead of letting Swift infer what types our array will hold, we can specify the type that we want.

As we can see, if we put in a value that does not match with the given type, our code will not compile.

However, it is possible to allow our arrays to hold any type. We can give it the special Any data type:

When adding values to our array, we must first initialize it with an original value. The following code will not compile:

We can initialize our array in the following ways:

var staff: [String] = []
var staff = [String]()

Dictionaries

Another common data structure that we might encounter are called dictionaries. These are similar to arrays except we use a key to access a value in the collection. In other words, dictionaries store key-value pairs.

var staffAge: [String: Int] = ["Vin": 19, "Richie": 20, "Antoinette": 4]

It is also common to break up our dictionary like so to keep things readable:

Notice that we used an append method to add elements to the end of the array. Swift provides many methods that we can use on our array, and we can even add our own! We can also use operators such as + to glue arrays together and return a new array. Read more about them in the .

Similar to arrays, Swift provides a lot of methods that we can use with dictionaries. The provides more information about them.

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Apple Documentation
Apple Documentation