Swift: The Complete Guide to Programming with Syntax, Debugging, and Concurrency

Notes on Usage....5

Dedication....28

1 Introduction....29

1.1 About this Book....30

1.2 Welcome to Swift!....34

1.3 Why Learn Swift?....37

1.4 Swift Versus Other Programming Languages....41

1.4.1 Python....41

1.4.2 Java....44

1.4.3 C....46

1.4.4 JavaScript....46

1.4.5 Dart....48

1.4.6 Kotlin....49

1.4.7 C....50

1.4.8 Rust....52

1.4.9 Picking the Ideal Language....54

1.5 Setting Up the Development Environment....58

1.5.1 Preparing Your Mac....58

1.5.2 Alternative Options for Swift Development....67

1.6 Summary....70

2 Variables....71

2.1 Variables....71

2.1.1 About Variables and Constants....73

2.1.2 Declaring Simple Variables and Constants....74

2.1.3 Type Annotations....77

2.1.4 Comments....81

2.2 Boolean....85

2.2.1 About Booleans....85

2.2.2 AND Operator....86

2.2.3 OR Operator....89

2.2.4 Nested Conditions....91

2.3 Numbers....94

2.3.1 Numeric Types....94

2.3.2 Arithmetic Operators....106

2.3.3 Comparison Operators....113

2.3.4 Numeric Literals....115

2.4 Text....121

2.4.1 About Strings....121

2.4.2 Basic String Literals....126

2.4.3 Multiline String Literals....126

2.4.4 Escape Sequences....127

2.4.5 Concatenation....130

2.4.6 String Interpolation....132

2.4.7 Checking String Contents....133

2.4.8 Substrings....138

2.4.9 Modifying Strings....142

2.4.10 Comparison Operators....145

2.4.11 StringNumber Conversion....148

2.4.12 Regular Expressions....155

2.5 Dates and Times....161

2.5.1 Basic Data Types....161

2.5.2 Arithmetic Operations....164

2.5.3 Comparison....168

2.5.4 Measuring Durations....171

2.5.5 StringDate Conversion....173

2.5.6 Internationalization....180

2.6 Quantities....184

2.6.1 Units....184

2.6.2 Measurement....186

2.6.3 Unit Conversions....188

2.6.4 Arithmetic Operations....190

2.7 Tuples....195

2.7.1 Basic Tuples....195

2.7.2 Named Tuples....198

2.7.3 Tuple Type Annotations....199

2.7.4 Comparison....200

2.8 Type Aliases....202

2.8.1 Basic Types....202

2.8.2 Complex Types....204

2.9 Summary....205

3 Collections....206

3.1 Arrays....208

3.1.1 Creating Arrays....208

3.1.2 Arrays as Constants....210

3.1.3 Accessing Arrays....212

3.1.4 Array Derivation....218

3.1.5 Modifying Arrays....225

3.1.6 Iterating Through Arrays....230

3.2 Sets....242

3.2.1 Creating Sets....244

3.2.2 Sets as Constants....246

3.2.3 Accessing Sets....246

3.2.4 Set Derivation....248

3.2.5 Checking for Supersets....257

3.2.6 Modifying Sets....258

3.2.7 Iterating Through Sets....261

3.3 Dictionaries....265

3.3.1 Creating Dictionaries....266

3.3.2 Dictionaries as Constants....273

3.3.3 Accessing Dictionaries....274

3.3.4 Modifying Dictionaries....277

3.3.5 Iterating Through a Dictionary....280

3.4 Summary....283

4 Control Flow....285

4.1 Conditional Statements....287

4.1.1 If-Else....288

4.1.2 Logical Operators....299

4.1.3 Ternary Operator....305

4.1.4 Nil-Coalescing Operator....309

4.1.5 Switch....313

4.2 Loops....324

4.2.1 For-In Loops....324

4.2.2 While Loops....337

4.2.3 Repeat-While Loops....341

4.3 Control Transfer Statements....346

4.3.1 Break....346

4.3.2 Continue....349

4.3.3 Fallthrough....352

4.3.4 Guard....357

4.4 Summary....362

5 Functions....363

5.1 What Is a Function?....363

5.2 Defining and Calling Functions....369

5.2.1 Defining a Function....369

5.2.2 Calling a Function from the Program....370

5.2.3 Calling a Function from Another Function....373

5.2.4 Variable Scope in Functions....376

5.3 Input Parameters....381

5.3.1 Named Parameters....381

5.3.2 Omitting Argument Labels....387

5.3.3 Default Arguments....390

5.3.4 Guarding Functions....393

5.4 Returning Values....396

5.4.1 Returning Single Values....396

5.4.2 Returning Multiple Values....401

5.5 Variadic Parameters....409

5.6 Function Overloading....414

5.7 Inout Parameters....419

5.8 Nested Functions....423

5.9 Function Types....429

5.9.1 Basic....429

5.9.2 Function Types as Parameter Types....434

5.9.3 Function Types as Return Types....438

5.10 Closures....441

5.10.1 Closure Expressions....442

5.10.2 Trailing Closures....448

5.10.3 Escaping Closures....451

5.10.4 Autoclosures....458

5.11 Generic Functions....461

5.11.1 Generic Functions....461

5.11.2 Type Constraints....465

5.11.3 Generic Where Clauses....473

5.12 Summary....476

6 Optionals....477

6.1 What Are Optionals?....477

6.1.1 Tuple Optionals....478

6.1.2 Simple Variable Optionals....481

6.1.3 Collection Optionals....483

6.1.4 Function Optionals....484

6.2 Optional Binding....487

6.3 Implicitly Unwrapped Optionals....492

6.4 Optional Chaining....494

6.5 Summary....497

7 Enumerations....498

7.1 What Are Enumerations?....498

7.2 Declaring Enumerations....502

7.2.1 Case Values....502

7.2.2 Raw Values....505

7.2.3 Associated Values....509

7.3 Computed Properties....515

7.4 Functions in Enumerations....521

7.5 Iterating over Enumerations....525

7.5.1 Iterating over Case Values....525

7.5.2 Iterating over Raw Values....526

7.5.3 Iterating over Associated Values....527

7.6 Recursive Enumerations....531

7.7 Generic Enumerations....536

7.8 Summary....539

8 Structs....540

8.1 What Is a Struct?....541

8.2 Declaring Structs....545

8.2.1 Basic Struct Declaration....545

8.2.2 Mutable Properties....547

8.2.3 Complex Properties....548

8.2.4 Nested Structs....549

8.2.5 Default Property Values....553

8.2.6 Optional Properties....554

8.3 Static Properties....557

8.4 Computed Properties....561

8.4.1 Getters....561

8.4.2 Setters....564

8.5 Functions....568

8.5.1 Initialization....568

8.5.2 Nonmutating Functions....570

8.5.3 Mutating Functions....573

8.5.4 Static Functions....574

8.6 Encapsulation....577

8.6.1 Private Properties....578

8.6.2 Private Functions....582

8.7 Structs as Function Parameters....585

8.8 Generic Structs....588

8.9 Advanced Features....592

8.9.1 Lazy Properties....592

8.9.2 Property Observers....596

8.9.3 Property Wrappers....598

8.9.4 Subscripts....601

8.9.5 Failable Initialization....604

8.10 Summary....608

9 Classes....609

9.1 Declaring Classes....611

9.1.1 Basic Class Declaration....612

9.1.2 Reference Semantics....613

9.1.3 Composition....618

9.2 Functions....625

9.2.1 Mutability....625

9.2.2 Deinitialization....626

9.2.3 Convenience Initialization....631

9.3 Inheritance....633

9.3.1 Superclasses and Subclasses....633

9.3.2 Overriding Functions....644

9.3.3 Overriding Initializers....648

9.3.4 Overriding Computed Properties....651

9.3.5 Overriding Subscripts....655

9.3.6 Casting....658

9.3.7 AnyObject Type....666

9.4 Classes as Function Parameters....671

9.5 Memory Management....675

9.5.1 Strong References....675

9.5.2 Weak References....680

9.5.3 Unowned References....684

9.6 Summary....687

10 Protocols....688

10.1 Purpose of Protocols....688

10.2 Function Requirements....695

10.2.1 Nonmutating Function....695

10.2.2 Mutating Function....699

10.2.3 Static Function....702

10.3 Initializer Requirements....705

10.4 Property Requirements....709

10.4.1 Get Requirement....709

10.4.2 Get Set Requirement....711

10.4.3 Static Requirement....713

10.5 Implementing Multiple Protocols....716

10.6 Checking for Protocol Conformance....721

10.7 Protocols as Function Parameters....724

10.7.1 Protocol Type....724

10.7.2 Existential Type....725

10.7.3 Opaque Type....727

10.8 Associated Types....730

10.9 Using Standard Protocols....734

10.9.1 Equatable....734

10.9.2 Comparable....738

10.9.3 Identifiable....743

10.9.4 Hashable....745

10.9.5 CustomStringConvertible....748

10.10 Summary....751

11 Extensions....752

11.1 Extending Enumerations....754

11.2 Extending Structs....758

11.3 Extending Classes....762

11.4 Extending Protocols....765

11.5 Operator Extensions....770

11.5.1 Arithmetic and Boolean Operators....770

11.5.2 Equality and Comparison Operators....773

11.5.3 Prefix and Postfix Operators....776

11.5.4 Custom Operators....778

11.6 Extending Swift Data Types....782

11.6.1 Sample Usage....782

11.6.2 Avoiding Name Conflicts....783

11.7 Generic Extensions....786

11.8 Summary....789

12 Error Handling....790

12.1 Understanding Errors in Swift....792

12.2 Throwing Errors....797

12.2.1 Throwing Built-in Errors....797

12.2.2 Throwing Custom Errors....799

12.2.3 Propagating Errors....803

12.3 Catching Errors....806

12.3.1 Direct Pattern Matching....806

12.3.2 Error Pattern Matching....811

12.3.3 Localized Error Messages....816

12.3.4 Optional Try....820

12.4 Cleanup with Defer....825

12.5 Runtime Checks....831

12.5.1 Debug Runtime Checks....832

12.5.2 Release Runtime Checks....837

12.6 Summary....841

13 File Handling....842

13.1 Text Files....843

13.1.1 Reading Text Files....844

13.1.2 Writing Text Files....849

13.2 Binary Files....855

13.2.1 Reading Binary Files....856

13.2.2 Writing Binary Files....861

13.3 Working with Common Formats....867

13.3.1 JSON....868

13.3.2 Property List....877

13.4 File System Operations....889

13.4.1 Examining Folders....889

13.4.2 Manipulating Folders....893

13.4.3 Examining Files....900

13.4.4 Manipulating Files....902

13.5 Summary....910

14 Concurrency....911

14.1 What Is Concurrency?....911

14.2 Async Functions....915

14.2.1 Writing Async Functions....915

14.2.2 Calling Async Functions....918

14.2.3 Running Functions in Parallel....928

14.3 Tasks....934

14.3.1 Creating Tasks....935

14.3.2 Task Groups....942

14.3.3 Task Priorities....952

14.3.4 Task Cancellation....960

14.4 Async Streams....965

14.4.1 Starting an Async Stream....966

14.4.2 Canceling an Async Stream....969

14.4.3 Handling Async Stream Errors....971

14.5 Shared State Safety....974

14.5.1 Task-Local Values....975

14.5.2 Detached Tasks....981

14.5.3 Actors....983

14.5.4 Sendable Types....988

14.6 Summary....995

15 Modules in Swift....997

15.1 Introduction to Modules....998

15.1.1 What Is a Module?....998

15.1.2 Why Use Modules?....1002

15.2 Working with Frameworks....1010

15.2.1 Setting Up a New Framework....1010

15.2.2 Adding Code to a Framework....1013

15.2.3 Building a Framework....1014

15.2.4 Importing a Framework....1016

15.3 Working with Packages....1022

15.3.1 Setting Up a New Package....1023

15.3.2 Adding Code to a Package....1025

15.3.3 Importing a Package....1026

15.4 Access Control....1032

15.4.1 Open....1032

15.4.2 Public....1033

15.4.3 Internal....1034

15.4.4 File Private....1035

15.4.5 Private....1035

15.5 Summary....1037

16 Conclusion....1038

A Unit Testing....1042

A.1 Introduction to Unit Testing....1042

A.1.1 What Is a Unit Test?....1043

A.1.2 Test-Driven Development....1045

A.1.3 Unit Testing in Swift....1047

A.2 Unit Testing with XCTest....1049

A.2.1 Preparing a Testable Project....1049

A.2.2 Coding Unit Tests....1052

A.2.3 Executing Unit Tests....1056

A.2.4 Assertions....1058

A.2.5 Test Coverage....1059

A.3 Unit Testing with Swift Testing....1062

A.3.1 Preparing a Testable Project....1062

A.3.2 Coding Unit Tests....1065

A.3.3 Executing Unit Tests....1068

A.3.4 Test Macros....1070

A.3.5 Test Coverage....1070

A.4 Summary....1072

B Debugging....1073

B.1 Debugging in Xcode....1074

B.1.1 Creating a Sample Project....1074

B.1.2 Setting Breakpoints....1075

B.1.3 Starting a Debug Session....1077

B.1.4 Running Through a Debug....1078

B.1.5 Changing Breakpoints During Debug....1082

B.2 Advanced Debugging Tools....1084

B.2.1 Conditional Breakpoints....1084

B.2.2 Symbolic Breakpoints....1087

B.2.3 Performance Debugging....1090

B.3 Support Commands....1094

B.4 Summary....1096

C The Author....1097

Index....1099

Service Pages....1132

Legal Notes....1136

This is your ultimate resource for Swift, the programming language for Apple devices! Get to know Swift’s syntax and learn to work with elements such as variables and collections. Use Swift’s built-in features for debugging, error handling, and memory management to streamline your development process. Then move to more advanced topics like concurrency and custom modules. Follow along with downloadable code examples to get practical experience working with the language. Become a Swift master in no time!

• Your comprehensive guide to the Swift programming language
• Work with variables, collections, enums, structs, and other language elements
• Practice as you learn with downloadable code snippets

Swift Syntax

Understand the elements of the Swift programming language. Learn to use variables, data types, and operators, and then string them together into collections. Implement control flow statements to execute your code based on predefined conditions.

Features and Programming Techniques

Work with object-oriented programming techniques in Swift using enums and structs. Improve your code using Swift’s variety of features, including Automatic Reference Counting for memory management, built-in debugging, and nil value management with optionals.

Coding with Swift

Start developing with Swift right away! Download code samples and follow line-by-line instructions for everything from your first “Hello, world!” to custom reusable modules.