Swift Fundamentals

Swift fundamentals with exercises.

Attention developer: Please read the Swift Language Guide on a topic or watch the YouTube complimentary video before going onto the Exercises section below.

YouTube Playlist - Swift Fundamentals

Table of Contents

1. The Basics

let swiftIntroduced = "2014"

Glossary

• Type Safety
• Variables
• Constants
• Type Annotation
• Type Inference
• String
• Int
• Float
• Double
• Boolean
• Tuples
• Optionals
• Optional Binding
• nil-coalescing

Video: Swift, The Basics

2. Basic Operators

9 % 4 // 1 

Glossary

• Arithmetic operators: +, *, -, /
• Remainder or modulo operator %
• Ternary operator (condition) ? :
• Unary operator
• Binary operator
• Assignment opeator
• Compound statements
• Comparison operators >, <, <=, >=, ==, !=
• Closed-range
• Half-open range
• One-sided range
• Logical operators &&, ||, !a

Video - Swift Basic Operators

3. Strings and Characters

let char: Character = "🚀"

Glossary

• String literal
• Multi-line String
• Special characters / escape characters
• Sring initialization syntax
• Value types
• Character
• Concatenaton
• String interpolation
• Unicode
• String.Index
• Substrings
• Prefix and Suffix

1. Video - Strings and Characters
2. Strings and Characters code examples

4. Collection Types

let languages = ["C", "Java", "Objective-C", "Swift", "JavaScript"]

Glossary

• Array
• Iterate
• Dictionary
• Set
• enumerated()

Arrays

1. Video - Arrays
2. Arrays code examples

Sets

1. Video - Sets
2. Sets code examples

Dictionaries

1. Video - Dictionaries
2. Dictionaries code examples

5. Control Flow

print("Please enter a number between 1 and 20 ?")
var input = Int(readLine() ?? "") ?? 2

if !(1...20).contains(input) {
  input = 2 
}

repeat {
  print("Swift is awesome! 😎")
  input -= 1
} while input > 0

Glossary

• switch
• control transfer statements: continue, break, fallthrough
• labeled statements
• for-in loop
• while
• repeat-while
• iterate
• enumerated()

1. Video: Control Flow
2. Control Flow code examples

6. Functions

func developerStatus() -> String {
  return "Always learning!"
}

Glossary

• input
• output
• variadic parameters
• in-out parameters
• guard
• return
• parameter
• implicit return
• argument

1. Video: Functions
2. Functions code examples

7. Closures

let add: (Int, Int) -> Int = { $0 + $1 }
add(12, 7) // 19

Glossary

• trailing closure syntax
• shorthand-syntax
• capturing values
• reference type
• @escaping closure
• implicit return
• multiple trailing closures

1. Video: Closures
2. Closures code examples

8. Enumerations

enum AppError: Error {
  case decodingError(Error) 
  case badURL(String)
  case badStatusCode(String)
}

Glossary

• CaseIterable
• Associated Values
• Raw Values
• Implicitly assigned Raw Values

Introduction to enums

1. Video: Enumerations
2. Enums code examples

Methods and Properties in enums

1. Video: Enums - Methods and Properties
2. Code examples

9. Structures

struct Venue {
  let address: String 
  let name: String 
  let latitude: Double
  let longitude: Double
}

Glossary

• Memberwise Initializer
• Value type
• mutating func
• Immutable

10. Classes

class Person {
  let name: String 
  let age: Int
  init(name: String, age: Int) {
    self.name = name 
    self.age = age
  }
}

class Fellow: Person {
  // inherits all properies and methods of the Person parent class    
}

Glossary

• inheritance
• deintializers
• reference type
• pointer
• retain cycle
• identity operator ===

11. Properties

var fullName: String {
  return firstName + " " + lastName
}

Glossary

• stored property
• computed property
• lazy property
• setter
• getter
• propety observer
• property wrappers
• Type property
• Instance property

12. Methods

Instance Method

struct Person {
  let name: String 
  
  func info() {
    print("My name is \(name)")
  }
}

let person = Person(name: "Alex")
person.info() // instance method

Type Method

struct Person {
  let name: String 
  
  static func getRaces() -> [String] {
    return ["Black", "Asian", "White", "LatinX"]
  }
  
  func info() {
    print("My name is \(name)")
  }
}

Person.getRaces() // type method

Glossary

• Type method
• Instance method
• self
• mutating func
• @discardableResult

13. Subscripts

struct Person {
  subscript(_ address: String) -> String {
    return geocode(address)
  }
}

let person = Person() 
print(person["105 Broadway, New York, NY"]) // 11249

14. Inheritance

class VenueCell: UICollectionViewCell {
  // VenueCell inherits all functions and properties from its Parent class, UICollectionViewCell
}

Glossary

• Overriding
• Subclassing
• final
• Base class
• Super class

15. Initialization

class Node {
  var value: Int 
  var next: Node? 
  init(_ value: Int) {
    self.value = value
  }
}

Glossary

• Default initializers
• Memberwise initializers
• Designated initializers
• Convenient initializers
• Failable initializers
• Required initializers

16. Deinitialization

deint only works within classess

class ItemViewController: UIViewController {
  deinit {
    // do any cleanup code or remove any notifications or listeners e.g Firebase listener
  }
}

17. Optional Chaining

struct Person {
  var name: String
  var phone: Phone?  

  struct Phone {
    var work: String? 
    var home: String?
  }
}

let person = Person(name: "Alice", phone: Person.Phone(work:"917-457-3498", home: nil))

if let workPhone = person.phone?.work {
  print("\(person.name)'s work phone number is \(workPhone)'")
  // Alice's work phone number is 917-457-3498
} else {
  print("\(person.name) does not have a work phone number.")
}

18. Error Handling

enum AppError: Error {
  case badYear
  case noData 
  case serverError
}

func currentYear(_ year: Int) throws {
  if year == 2020 {
    throw AppError.badYear
  }
  print("Fingers crossed this is a great year for us all.")
}

do {
  try currentYear(2020)
} catch {
  print(error) // badYear
}

do {
  try currentYear(2021) // Fingers crossed this is a great year for us all.
} catch {
  print(error)
}

Glossary

• throw
• throws
• do-catch
• try, try? and try!
• Error

19. Type Casting

Downcasting

class Person {
  func info() {
    print("This is a person.")
  }
}

class Fellow: Person {
  override func info() {
    print("This person is a fellow.")
  }
}

class Singer: Person {
  override func info() {
    print("This person is a singer.")
  }
}

let heather = Fellow()
let bob = Singer()
let people = [bob, heather]

if let person = people[0] as? Singer { // downcast from Person object to a Singer object
  person.info() // This person is a singer.
}

Type checking

let objects: [Any] = ["Alex", true, 2021]

if objects[0] is String {
  print("\(objects[0]) is a String object.") // Alex is a String object.
}

if objects[1] is Bool {
  print("\(objects[1]) is a Bool instance.") // true is a Bool instance.
}

Glossary

• downcasting
• as!, as?, as
• type checking

Exercises

Complete the exercise in Swift Playground or an online IDE like repl.it .

1. The Basics, Basic Operators
2. Strings and Characters
3. Collection Types - Arrays
4. Collection Types - Dictionaries
5. Collection Types - Sets
6. Control Flow
7. Optionals
8. Functions
9. Closures
10. Enumerations
11. Structs

Projects

To evaluate your Swift fundamentals work on any of the following projects as a command line macOS application.

• Black Jack
• Mad Libs Generator
• Rock, Paper, Scissors
• Tic Tac Toe
• Hangman
• Calculator
• Trivia Game
• Text-Based Adventure Game