book

Head First Swift

by Jon Manning, Paris Buttfield-Addison

November 2021

Beginner

436 pages

9h 41m

English

O'Reilly Media, Inc.

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Authors of Head First Swift
Table of Contents (the real thing)
how to use this book: Intro
Who is this book for?Who should probably back away from this book?We know what you’re thinkingWe know what your brain is thinkingMetacognition: thinking about thinkingHere’s what WE didHere’s what YOU can do to bend your brain into submissionRead meThe technical review teamO’Reilly Online LearningAcknowledgments
1. Introducing Swift: Apps, Systems, and Beyond!
Swift is a language for everythingThe swift evolution of SwiftSwift into the futureHow you’re going to write SwiftThe path you’ll be takingGetting PlaygroundsDownloading and installing Playgrounds on macOSCreating a PlaygroundUsing a Playground to code SwiftBasic building blocksA Swift exampleHere’s what you need to buildThe print function1 Building a list of ingredients2 Picking four random ingredients3 Displaying our random pizzaCongrats on your first steps with Swift!SwiftcrossSwiftcross Solution
2. Swift by Name: Swift by Nature
Building from the blocksBasic operatorsOperating swiftly with mathematicsExpress yourselfExpressing yourselfNames and types: peas in a podNot all data is numbersThese are all typesSwift SafetyStringing things along with typesWho am I?String interpolationSwiftcrossSwiftcross SolutionWho am I Solution?
3. Collecting and Controlling: Going Loopy for Data
Sorting pizzasSwift collection typesCollecting values in an arrayHow big is that array, exactly? Is it empty?Collecting values in a setCollecting values in a dictionaryTuplesEveryone needs a good aliasControl flow statementsif statementsswitch statementsBuilding a switch statementStart with the switch keywordRange operatorsMore complex switch statementsGetting repetitive with loopsBuilding a for loopBuilding a while loopBuilding a repeat-while loopSolving the pizza-sorting problemPhew, that’s a lot of Swift!Code MagnetsPool PuzzleBE the Swift CompilerSwiftcrossCode Magnets SolutionPool Puzzle SolutionBE the Swift Compiler SolutionSwiftcross Solution
4. Functions and Enums: Reusing Code on Demand
Functions in Swift let you reuse codeWhat can functions do?Built-in functionsWhat can we learn from built-in functions?Improving the situation with a functionWriting the body of the functionUsing functionsFunctions deal in valuesMany happy returns (from your functions)But Swift is meant to make things simple...A variable number of parametersFireside ChatsWhat can you pass to a function?Every function has a typeFunction types as parameter typesMultiple return typesFireside ChatsFunctions don’t have to stand aloneNested functionsSwitching with enumsFunctioncrossFunctioncross Solution
5. Closures: Fancy, Flexible Functions
Meet the humble closureClosures are better with parametersBoiling it all down to something usefulThe problemThe solutionReducing with closuresCapturing values from the enclosing scopeWhat came first, the function or the closure?Escaping closures: the contrived exampleAutoclosures provide flexibilityThe situationThe problemThe solutionShorthand argument namesClosurecrossBE the Swift CompilerClosurecross SolutionBE the Swift Compiler Solution
6. Structures, Properties, and Methods: Custom Types and Beyond
Let’s make a pizza, in all its glory...A Pizza structUnder the hood...The initializer behaves just like a functionAccess control and structsMethods inside structuresChanging properties using methodsComputed propertiesCreating a property observerCode MagnetsGetters and setters for computed propertiesImplementing a setterSwift Strings are actually structsThe case for lazy propertiesUsing lazy propertiesStructcrossStructcross SolutionCode Magnets Solution
7. Classes, Actors, and Inheritance: Inheritance Is Always a Thing
A struct by any other name (that name: a class)Inheritance and classesReplacing Overriding methodsHere’s our Plant class:Here’s our Succulent child class, overriding a method of the parent:Under the hood...Final classesAutomatic reference countingMutabilityBewareSwift SafetyFireside ChatsBE the Swift CompilerPool PuzzleClasscrossPool Puzzle SolutionBE the Swift Compiler SolutionClasscross Solution

8. Protocols and Extensions: A Swift Lesson in Protocol
The Robot FactoryThe problem:A solution:Protocol inheritanceMutating methodsProtocol types and collectionsComputed properties in extensionsUseful extensions and youAdding an initializer (with an extension)Extending a protocolUseful protocols and you Protocol composition Conforming to Swift’s protocolsSequencesConforming to Sequence and IteratorProtocol:Using your new sequence:EquatableThe problemConforming to Equatable:Implementing ==Code MagnetsProtocolcrossBE the Swift CompilerCode Magnets SolutionProtocolcross SolutionBE the Swift Compiler Solution
9. Optionals, Unwrapping, Generics, and More: Nothing Optional About It
Optionals ExposedDealing with something that’s missingThe problemWhy you might need an optionalThe struct for Josh is good, it represents Josh reasonably well: Josh is named “Josh”, and they’ve consumed 5 coffees.But the struct for Tom doesn’t really represent them. They haven’t really consumed 0 coffees; they don’t drink it at all.Optionals and handling missing data A Person Alex and Tom Unwrapping optionals Unwrapping optionals with guard Using guard let to unwrap an optional:Force unwrappingSwift SafetyBE the Swift CompilerSwift SafetyGenericsQueue requirementsA queue with genericsHere’s our new Queue typeUsing your QueueOptionalcrossOptionalcross SolutionBE the Swift Compiler Solution
10. Getting Started With Swiftui: User Interfaces…Swiftly
What’s a UI framework, anyway?Your first SwiftUI UIUI building blocksMaking a list, checking it…quite a few times, to get it perfectUser interfaces with stateButtons are for pressingLet’s see how far you’ve come Customizing your views with modifiers Using view modifiers:Order matters (sometimes):Create a new SwiftUI Xcode project, for iOSYour Xcode will look something like thisCreate a new type to store a todo item inMake sure each todo item can be uniquely identifiedCreate a user interface for the appWhat’s going on in this user interface?Create a user interface for the app, continued, continuedMaking the List actually list todosTest DriveImplement a way to save the list of todosSo, that’s a UI framework?SwiftUIcrossPool PuzzleBE the Swift CompilerSwiftUIcross SolutionPool Puzzle SolutionBE the Swift Compiler Solution
11. Putting Swiftui into Practice: Circles, Timers, Buttons—Oh My!
What fancy things can be done with a UI framework?Create a new SwiftUI Xcode project, for iOSThe Executive Timer UI and featuresThis is what our Executive Timer UI will look like, and do:And this is what the UI will look like in the various different states:Creating the basic elements of the appPieces of the UISetting up the UI of the Executive TimerCoding the pieces of the UI1 Coding the gray circle2 Coding the gray circle3 Coding the time and buttonsCombining the three elementsThe finishing touchesTest DriveTabbed views for a clean UI1 Create however many different views you need (to live in tabs)2 Build a TabView containing your viewsThe resulting tabsIf you created three views, and a TabView containing them, you might end up here:Creating a new tabbed ContentViewCreating the tabs and the TabView1 Create an empty TimerSettingsView view2 Add the second tab to the TabView in the ContentViewWe’re basically done! The Executive Timer now has tabs:Running your new tabbed Executive TimerSwiftUIcrossSwiftUIcross Solution
12. Apps, web, and Beyond: Putting It All Together
A journey must end...A recipe for a welcome screenStep by step assembly of the welcome screenSmash Share the stateIt’s time for our old friend...Here’s a type that represents the score of a game:Here’s some views that use our class:Building an app with multiple views that share stateHere’s the first view of our hypothetical app:Here’s the second view of our hypothetical app:Building a two-view score trackerHere’s what we’ll need to do:The ObservableObjectThe first viewThe second viewThe first view, againA fancy AsyncImageLike this:We do this:Meet Vapor, the Swift web framework1 You can make a new Vapor project with the following command:2 Change into the Vapor project’s directory with this command:3 Then run this to open the new Vapor project in Xcode:Sending data over the web with Vapor1 Create a new closure, with a dynamic parameter:2 Add a guard let to unwrap the optional parameter:3 Return what you need to return4 Visit your new URLSwiftUIcrossSwiftUIcrossSwiftUIcross Solution
Index

Content preview from Head First Swift

Chapter 9. Optionals, Unwrapping, Generics, and More: Nothing Optional About It

Note

It’s a funny joke because you can’t really avoid optionals.

Dealing with data that doesn’t exist can be challenging. Thankfully, Swift has a solution. Meet optionals. In Swift, an optional allows you to work with a value, or with the absence of a value. They’re one of the many ways that Swift is designed to be a safe language. You’ve occasionally seen optionals in your code so far, and now we’re going to explore them in more depth. Optionals make Swift safe because they keep you from accidentally writing code that would break if it’s missing data, or if something can sometimes return a value that isn’t actually a value.

Optionals Exposed

Today’s interview: the humble Optional

Head First: Thanks for joining us, Optional. We’re all very excited to get to know you a bit better.

Optional: No problem at all. I’m very popular these days, but I always make time to talk to people. Do you mind if I make notes about you while we talk?

Head First: About me? I’m talking to you to learn about you! But, I guess, sure. Whatever you need.

Optional: Thanks! What’s your favorite number?

Head First: I don’t really have one. Sorry. I’m told you’re one of Swift’s most powerful features. Care to comment on what ...

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