adwaita.docc/Tutorial/Essentials/Views.tutorial

@Tutorial {

    @Intro(title: "Create views") {
        This is a beginner tutorial. It shows how to create a simple "Hello, world!" app using ``Adwaita``.
        While there are instructions for building on macOS, _Adwaita for Swift_ works best on Linux.
    }

    @Section(title: "Introduction to views") {
        @ContentAndMedia {
            Let's start by taking a look at the code of the template view.
        }

        @Steps {
            @Step {
                Open the file `AdwaitaTemplate.swift`.

                `@main` sets this struct as the app's entry point. You'll use this only once per app on the structure conforming to ``App``.
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate1.swift")
            }
            @Step {
                The computed variable `scene` contains all the windows available in your app.
                A window contains _views_.

                You can call other views inside of views (such as the ``Text`` or `ToolbarView` in this example).
                Methods like ``View/padding(_:_:)`` and ``View/topToolbar(visible:_:)`` often used to tweak views or wrap views into other views (you'll get more familiar with them soon).
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate1.swift")
            }
            @Step {
                Read how views work in the article <doc:CreatingViews>.

                Then, try to create a view `ContentView` yourself that contains all the content of the window, and call it in the window.
                Find a possible solution in the next step.
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate1.swift")
            }
            @Step {
                This is a possible solution. You could find the types for the `ToolbarView` view properties in the file `ToolbarView.swift`.
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate2.swift")
            }
            @Step {
                Let's replace the text by a button, printing "Hello, world!" when it gets pressed.

                An overview of the standard widgets and their modifiers is available in the docs for ``Adwaita``. We'll discuss details later.
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate3.swift")
            }
        }
    }

    @Section(title: "State") {
        @ContentAndMedia {
            State is data that can be accessed in a view and its child views.
            To understand this section, make sure to have read <doc:CreatingViews>.
        }

        @Steps {
            @Step {
                Use the ``State`` property wrapper to add state.

                Are you able to extract only the button (without its modifiers) into an own view?
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate4.swift", previousFile: "AdwaitaTemplate3.swift")
            }
            @Step {
                You have to use the ``Binding`` property wrapper.
                @Code(name: "AdwaitaTemplate.swift", file: "AdwaitaTemplate5.swift")
            }
        }
    }

    @Assessments {
        @MultipleChoice {
            What code _could_ create an instance of the following view if used in the right context?
            ```swift
            struct ContentView: View {

                @Binding var section: String
                @State private var title = "Title"
                var app: GTUIApp

                var view: Body {
                    ...
                }

            }
            ```

            @Choice(isCorrect: false) {
                ```swift
                ContentView()
                ```
                @Justification {
                    You must provide values for properties that don't get a default value.
                }
            }
            @Choice(isCorrect: true) {
                ```swift
                ContentView(section: $section, app: app)
                ```
                @Justification {
                    You need to pass a value for `section` and `app`. As `title` is a state value and therefore private to the view, it has to receive a default value inside the view and cannot be determined from outside the view.
                }
            }
            @Choice(isCorrect: false) {
                ```swift
                ContentView(section: $section, title: "Title", app: app)
                ```
                @Justification {
                    State values are private to a view. You cannot pass values from outside to them.
                }
            }
            @Choice(isCorrect: false) {
                ```swift
                ContentView($section, "Title", app)
                ```
                @Justification {
                    In Swift, argument labels are required when passing parameters to a view. Also, a state value cannot be accessed from outside the view.
                }
            }
        }
    }



}