Learning Swift 2 Programming

Jacob Schatz is a senior software engineer with more than eight years of experience writing code for the masses. His code is often used by millions of people, and his advice is often sought. Jacob also goes by the name Skip Wilson and has a popular YouTube channel currently covering Swift and Python. Jacob is always selectively consuming the latest programming trends. He has a passion for making a difference and is constantly solving problems. Lately he has been deep into Swift, but he also writes tons of JavaScript, Python, Objective-C, and other languages. He is always learning more languages and thoroughly enjoys making new things. He is, at heart, a pedagogue, and he enjoys teaching and finding new ways to explain advanced concepts.

Introduction 1

1 Getting Your Feet Wet: Variables, Constants, and Loops 5
Building Blocks of Swift 6
 Computed Properties (Getters and Setters) 6
 Using Comments 8
 Inference 8
Merging Variables into a String 10
Optionals: A Gift to Unwrap 11
 Printing Your Results 14
 Implicitly Unwrapped Optionals 14
Tuples 15
Number Types 16
From Objective-C to Swift 17
 Control Flow: Making Choices 18
 Switching It Up: switch Statements 25
 Stop...Hammer Time 28
Summary 29

2 Collecting Your Data: Arrays and Dictionaries 31
Using Arrays 31
 Your First Array the Long Way 31
 A Quicker Array 32
 Using AnyObject 32
 Differences Between NSArrays and Swift Arrays 33
Modifying Arrays 33
 Accessing Array Elements 33
 Adding Elements to an Array 34
 Removing Elements from Arrays 34
 Iterating Over Arrays 35
 Extra Bits of Arrays 35
 Emptying an Array 36
Using Dictionaries 36
 Adding, Removing, and Inserting with Dictionaries 37
 Iterating Over Dictionaries 37
 Extra Bits of Dictionaries 38
 Emptying a Dictionary 38
 Testing Dictionaries for the Presence of Values 38
 Putting It All Together 39
Summary 41

3 Making Things Happen: Functions 43
Defining Functions 44
 Return Types 45
 Multiple Return Values 46
More on Parameters 47
 External Parameter Names 47
 Default Parameter Values 48
 Variadic Parameters 49
 In-Out Parameters 50
 Functions as Types 51
 Putting It All Together 52
Summary 55

4 Structuring Code: Enums, Structs, and Classes 57
Enums 58
 Which Member Was Set? 59
 Associated Values 59
 Raw Values 60
Structs 61
 Defining Methods in Structs 63
 Structs Are Always Copied 64
 Mutating Methods 65
 Classes 66
 Initialization 66
 What Is a Reference Type? 68
 Do I Use a Struct or a Class? 68
 Forgot Your Pointer Syntax? 69
 Property Observers 69
 Methods in Classes 70
Summary 74

5 SpriteKit 75
Introducing SpriteKit 75
 The SKNode and SKSpriteNode 75
Creating a Game 76
 The New Project Screen 76
 The Game 85
Summary 92

6 Reusable Code: Closures 93
What Are Closures? 93
Closures in Other Languages 94
How Closures Work and Why They’re Awesome 95
 The Closure Syntax 96
 Inferring Using Context 96
 Arguments Have a Shorthand, Too 97
 Sorting a Custom Car Class 97
 Closures Are Reference Types 98
 Automatic Reference Counting 99
 Strong Reference Cycles 100
 Trailing Closures 106
Summary 107

7 Creating Your Own Syntax: Subscripts and Advanced Operators 109
Writing Your First Subscript 110
Bits and Bytes with Advanced Operators 113
 Bitwise NOT 114
 Bitwise AND 115
 Bitwise OR 116
 Bitwise XOR 117
 Shifting Bits 118
 UInt8, UInt16, UInt32, Int8, Int16, Int32, and So On 119
 Value Overflow and Underflow 119
Customizing Operators 120
Making Your Own Operators 122
Bits and Bytes in Real Life 123
Summary 127

8 Protocols 129
Writing Your First Protocol 129
 Properties 131
Animizable and Humanizable 134
 Methods 135
Delegation 136
Protocols as Types 138
Protocols in Collections 139
 Protocol Inheritance 140
 Protocol Composition 141
 Protocol Conformity 143
 Optional Protocol Prerequisites 145
Optional Chaining 146
 Back to Optional Protocol Requisites 148
 Useful Built-in Swift Protocols 149
Summary 151

9 Becoming Flexible with Generics 153
The Problem That Generics Solve 153
 Other Uses for Generics 155
 Generics for Protocols 157
 The where Clause 158
Summary 162

10 Games with SpriteKit 163
The Game 163
The Setup 163
Tour the Code 164
The Game 164
 Step 1: Create the World 165
 Step 2: Making Things Move 176
Summary 185

11 Making Games with Physics 187
Making a Physics-Based Game 187
 Creating the Project 188
 Adding the Assets 189
 Adding the Levels 189
 Generating the Levels 190
 Making a Playable Game 197
 Creating the Cage 199
Summary 204

12 Making Apps with UIKit 205
Application Types 205
 Single-View Applications 206
 Creating the User Interface 208
 Adding Constraints 209
 Hooking Up the UI to Code 211
 Writing the Code 212
 The TableView 216
Summary 218

Index 219