Book Image

Swift 3 Object-Oriented Programming - Second Edition

By : Gaston C. Hillar
Book Image

Swift 3 Object-Oriented Programming - Second Edition

By: Gaston C. Hillar

Overview of this book

Swift has quickly become one of the most-liked languages and developers’ de-facto choice when building applications that target iOS and macOS. In the new version, the Swift team wants to take its adoption to the next level by making it available for new platforms and audiences. This book introduces the object-oriented paradigm and its implementation in the Swift 3 programming language to help you understand how real-world objects can become part of fundamental reusable elements in the code. This book is developed with XCode 8.x and covers all the enhancements included in Swift 3.0. In addition, we teach you to run most of the examples with the Swift REPL available on macOS and Linux, and with a Web-based Swift sandbox developed by IBM capable of running on any web browser, including Windows and mobile devices. You will organize data in blueprints that generate instances. You’ll work with examples so you understand how to encapsulate and hide data by working with properties and access control. Then, you’ll get to grips with complex scenarios where you use instances that belong to more than one blueprint. You’ll discover the power of contract programming and parametric polymorphism. You’ll combine generic code with inheritance and multiple inheritance. Later, you’ll see how to combine functional programming with object-oriented programming and find out how to refactor your existing code for easy maintenance.

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Table of Contents (17 chapters)
Swift 3 ObjectOriented Programming - Second Edition
Swift 3 ObjectOriented Programming - Second Edition
Credits
Credits
About the Author
About the Author
Acknowledgement
Acknowledgement
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Customer Feedback
Customer Feedback
Preface
Preface
Free Chapter
1
Objects from the Real World to the Playground
Objects from the Real World to the Playground
Installing the required software on Mac OS
Installing the required software on Ubuntu Linux
Working with Swift 3 on the web
Capturing objects from the real world
Generating classes to create objects
Recognizing variables and constants to create properties
Recognizing actions to create methods
Organizing classes with UML diagrams
Working with API objects in the Xcode Playground
Exercises
Test your knowledge
Summary
2
Structures, Classes, and Instances
Structures, Classes, and Instances
Understanding structures, classes, and instances
Understanding initialization and its customization
Understanding deinitialization and its customization
Understanding automatic reference counting
Declaring classes
Customizing initialization
Customizing deinitialization
Creating the instances of classes
Exercises
Test your knowledge
Summary
3
Encapsulation of Data with Properties
Encapsulation of Data with Properties
Understanding elements that compose a class
Declaring stored properties
Generating computed properties with setters and getters
Combining setters, getters, and a related property
Understanding property observers
Transforming values with setters and getters
Creating values shared by all the instances of a class with type properties
Creating mutable classes
Building immutable classes
Exercises
Test your knowledge
Summary
4
Inheritance, Abstraction, and Specialization
Inheritance, Abstraction, and Specialization
Creating class hierarchies to abstract and specialize behavior
Understanding inheritance
Declaring classes that inherit from another class
Overriding and overloading methods
Overriding properties
Controlling whether subclasses can or cannot override members
Working with typecasting and polymorphism
Taking advantage of operator overloading
Declaring compound assignment operator functions
Declaring unary operator functions
Declaring operator functions for specific subclasses
Exercises
Test your knowledge
Summary
5
Contract Programming with Protocols
Contract Programming with Protocols
Understanding how protocols work in combination with classes
Declaring protocols
Declaring classes that adopt protocols
Taking advantage of the multiple inheritance of protocols
Combining inheritance and protocols
Working with methods that receive protocols as arguments
Downcasting with protocols and classes
Treating instances of a protocol type as a different subclass
Specifying requirements for properties
Specifying requirements for methods
Combining class inheritance with protocol inheritance
Exercises
Test your knowledge
Summary
6
Maximization of Code Reuse with Generic Code
Maximization of Code Reuse with Generic Code
Understanding parametric polymorphism and generic code
Declaring a protocol to be used as a constraint
Declaring a class that conforms to multiple protocols
Declaring subclasses that inherit the conformance to protocols
Declaring a class that works with a constrained generic type
Using a generic class for multiple types
Combining initializer requirements in protocols with generic types
Declaring associated types in protocols
Creating shortcuts with subscripts
Declaring a class that works with two constrained generic types
Using a generic class with two generic type parameters
Inheriting and adding associated types in protocols
Generalizing existing classes with generics
Extending base types to conform to custom protocols
Test your knowledge
Exercises
Summary
7
Object-Oriented and Functional Programming
Object-Oriented and Functional Programming
Refactoring code to take advantage of object-oriented programming
Understanding functions as first-class citizens
Working with function types within classes
Creating a functional version of array filtering
Writing equivalent closures with simplified code
Creating a data repository with generics and protocols
Filtering arrays with complex conditions
Using map to transform values
Combining map with reduce
Chaining filter, map, and reduce
Solving algorithms with reduce
Exercises
Test your knowledge
Summary
8
Extending and Building Object-Oriented Code
Extending and Building Object-Oriented Code
Putting together all the pieces of the object-oriented puzzle
Adding methods with extensions
Adding computed properties to a base type with extensions
Declaring new convenience initializers with extensions
Defining subscripts with extensions
Working with object-oriented code in iOS apps
Adding an object-oriented data repository to a project
Interacting with an object-oriented data repository through Picker View
Exercises
Test your knowledge
Summary
9
Exercise Answers
Exercise Answers
Chapter 1, Objects from the Real World to Playground
Chapter 2, Structures, Classes, and Instances
Chapter 3, Encapsulation of Data with Properties
Chapter 4, Inheritance, Abstraction, and Specialization
Chapter 5, Contract Programming with Protocols
Chapter 6, Maximization of Code Reuse with Generic Code
Chapter 7, Object-Oriented Programming and Functional Programming
Chapter 8, Protection and Organization of Code

Creating values shared by all the instances of a class with type properties

The LionSuperHero class is a blueprint for lions that are superheroes. This class should inherit from the SuperHero class, but we will forget about inheritance and other super types of superheroes for a while and use the LionSuperHero class to understand the difference between type and instance properties.

We will define the following type properties to store the values that are shared by all the members of the lion superhero group:

  • averageStrength: This is the average strength of the superhero group.

  • averageRunningSpeed: This is the average running speed of the superhero group.

  • attackPower: This is the attack power score of the superhero group.

  • defensePower: This is the defense power score of the superhero group.

  • warriorScore: This is the score that combines the previously mentioned values in a single value that determines the warrior score of the superhero group. It is a calculated type property.

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