Beginning Swift Programming

Wei–Meng Lee is a technologist and founder of Developer Learning Solutions (www.learn2develop.net), a technology company specializing in hands–on training on the latest mobile technologies. He is an established developer and trainer specializing in .NET, iOS, and Android. Wei–Meng speaks regularly at international conferences and has authored and co–authored numerous books on .NET, XML, and mobile technologies. He writes extensively for the O Reilly Network and Mobiforge.com on topics ranging from .NET to Mac OS X. He is also the author of Beginning iOS 5 Application Development and Beginning Android 4 Application Development, both from Wrox.

INTRODUCTION xxiii


CHAPTER 1: INTRODUCTION TO SWIFT 1


What Is Swift? 2


Why Swift Is Important 3


Setting Up the Environment 3


Creating a Playground Project 4


Creating an iOS Project 6


Swift Syntax 10


Constants 10


Variables 12


String Interpolation: Including Values in Strings 14


Statements 14


Printing 15


Comments 15


Summary 17


CHAPTER 2: DATA TYPES 19


Basic Data Types 20


Integers 20


Types of Integers 21


Integer Operations 22


Integer Literals 22


Floating?]Point Numbers 23


Floating?]Point Operations 23


Floating?]Point Literals 24


Type Alias 25


Boolean 25


Tuples 26


Optional Types 27


Implicitly Unwrapped Optionals 28


Optional Binding 29


Unwrapping Optionals Using ? 30


Enumerations 30


Using Enumeration in Switch Statements 31


Enumeration Raw Values 32


Auto?]Increment for Raw Values 33


Associated Values 34


Enumeration Functions 35


Summary 36


CHAPTER 3: STRINGS AND CHARACTERS 39


Strings 40


Mutability of Strings 40


Strings as Value Types 40


Characters 41


Concatenating Strings 43


Special Characters 44


Unicode 45


Common String Functions 46


Equality 46


Prefi x and Suffi x 47


Length 47


Substrings 48


Converting Strings to Arrays 51


Type Conversion 51


Interoperability with NSString 52


Casting String to NSString 53


Using NSString Directly 54


String or NSString? 55


Summary 56


CHAPTER 4: BASIC OPERATORS 59


Assignment Operator 60


Arithmetic Operators 61


Addition Operator 61


Subtraction Operator 62


Multiplication Operator 62


Division Operator 63


Modulus Operator 63


Increment and Decrement Operator 63


Compound Assignment Operators 65


Nil Coalescing Operator 65


Comparison Operators 66


Equal To and Not Equal To 66


Greater Than or Equal To 67


Less Than or Equal To 67


Range Operators 68


Logical Operators 69


NOT 69


AND 70


OR 71


Combining Logical Operators 71


Ternary Conditional Operator 72


Summary 73


CHAPTER 5: FUNCTIONS 75


Defi ning and Calling a Function 76


Input Parameters 76


Returning a Value 76


Returning Multiple Values 77


Function Parameter Names 77


External Parameter Names Shorthand 79


Default Parameter Values 79


Variadic (Variable) Parameters 80


Constant and Variable Parameters 81


In?]Out Parameters 82


Function Types 83


Defining a Function Type Variable 83


Calling a Function Type Variable 84


Returning Function Type in a Function 85


Nested Functions 85


Summary 86


CHAPTER 6: COLLECTIONS 89


Arrays 90


Mutability of Arrays 90


Array Data Types 90


Retrieving Elements from an Array 91


Inserting Elements into an Array 91


Modifying Elements in an Array 92


Appending Elements to an Array 92


Checking the Size of an Array 93


Removing Elements from an Array 93


Iterating over an Array 93


Creating an Empty Array 94


Testing Arrays for Equality 95


Dictionaries 96


Mutability of Dictionaries 97


Retrieving Elements from a Dictionary 97


Checking the Size of a Dictionary 98


Modifying an Item in the Dictionary 98


Removing an Item from the Dictionary 99


Iterating over a Dictionary 99


Creating an Empty Dictionary 101


Testing Dictionaries for Equality 101


Copying the Behavior of Arrays and Dictionaries 102


Summary 103


CHAPTER 7: CONTROL FLOW AND LOOPING 107


Flow Control 108


If Statement 108


If?]Else Statement 109


Switch Statement 110


Matching Numbers 111


Matching Characters 112


Fallthrough 112


Matching a Range of Numbers 113


Matching Tuples 114


Value Bindings 115


Where Clause 117


Looping 118


For?]In Loop 118


Traditional For Loop 121


While Loop 122


Do?]While Loop 123


Control Transfer Statements 124


Break Statement 124


Continue Statement 126


Labeled Statement 126


Summary 128


CHAPTER 8: STRUCTURES AND CLASSES 131


Structures 132


Memberwise Initializers 132


Structures as Value Types 133


Comparing Structures 135


Classes 135


Defining a Class 136


Properties 136


Stored Properties 136


Lazy Stored Properties 137


Computed Properties 138


Motivation Behind Computed Properties 139


The newValue keyword 140


Read?]Only Computed Properties 141


Property Observers 141


Typed Properties 143


Initializers 144


Initializers and External Parameter Names 145


Initializing Variables and Constants During Initialization 147


Classes as Reference Types 147


Comparing Instances Identity Operators 149


Comparing Instances Equivalence Operators 150


Methods in Classes 151


Instance Methods 151


Local and External Parameter Names for Methods 152


The self Property 154


Type Methods 155


Methods in Structures 155


Summary 157


CHAPTER 9: INHERITANCE 161


Understanding Inheritance 162


Defi ning a Base Class 162


Instantiating a Base Class 162


Creating an Abstract Class 163


Inheriting from a Base Class 164


Overriding Initializers 164


Overloading Initializers 165


Creating Abstract Methods 167


Overloading Methods 169


Preventing Subclassing 170


Types of Initializers 171


Default Initializer 171


Designated Initializers 172


Convenience Initializers and Initializer Chaining 174


Calling Initializers in Subclasses 176


Extensions 177


Extending Methods 177


Extending Properties 177


Access Controls 178


Internal 179


Private 180


Public 181


Summary 181


CHAPTER 10: CLOSURES 185


Understanding Closures 186


Functions as Closures 186


Assigning Closures to Variables 187


Writing Closures Inline 188


Type Inference 188


Shorthand Argument Names 189


Operator Function 190


Trailing Closures 190


Using the Array s Three Closure Functions 190


The map Function 191


Example 1 191


Example 2 192


The filter Function 192


Example 1 192


Example 2 193


The reduce Function 194


Example 1 194


Example 2 195


Using Closures in Your Functions 196


Summary 198


CHAPTER 11: PROTOCOLS AND DELEGATES 201


Understanding Protocols 202


Defining and Using a Protocol 202


Conforming to a Protocol 202


Optional Methods 204


Conforming to Multiple Protocols 206


Property Requirements 206


Initializer Requirements 207


Understanding Delegates 207


Delegates as Event Handlers 208


A Practical Example of Protocols and Delegates 211


Summary 213


CHAPTER 12: GENERICS 217


Understanding Generics 218


Using Generic Functions 218


Multiple Type Parameters 219


Specifying Type Constraint 220


Generic Types 221


Generic Classes 221


Generic Structures 223


Generic Type Extension 224


Using Generics in Protocols 225


Specifying Requirements for Associated Types 228


Summary 229


APPENDIX: EXERCISE ANSWERS 233


INDEX 247