.NET MAUI Project Structure

• .NET MAUI is a framework for building cross-platform applications with C# and .NET.

Building Blocks in .NET MAUI Projects

• MauiProgram.cs contains the code for creating and configuring the Application object.
• App.xaml and App.xaml.cs provides UI resources and sets up the initial application window.
• AppShell.xaml and AppShell.xaml.cs specifies the application's initial page and manages page registration for navigation.
• MainPage.xaml and MainPage.xaml.cs define the layout and UI logic for the default page.
• A .NET MAUI project includes default resources like images, icons, fonts, and bootstrap code for each platform.

Application Class

• The App class represents the .NET MAUI application and inherits from Microsoft.Maui.Controls.Application.
• The App class is instantiated and loaded by platform-specific bootstrap code.
• The App class constructor typically creates an AppShell instance and assigns it to the MainPage property.
• The code sets the first screen displayed to the user based on the AppShell definition.
• The App class includes methods for handling application lifecycle events, such as when the app is sent to the background.
• It also includes methods for creating new windows.
• A .NET MAUI app defaults to a single window but can create additional windows for desktop and tablet applications.

Navigation Structures with Shell

• .NET MAUI Shell simplifies app development by offering essential features.
• Shell provides a single location to define the app's visual hierarchy.
• It delivers a consistent navigation experience.
• Shell uses a URI-based navigation scheme, allowing navigation to any page.
• It has an integrated search handler.
• In a .NET MAUI Shell app, the visual hierarchy is described in a class that subclasses the Shell class.
• This class utilizes three main hierarchical objects: FlyoutItem or TabBar, Tab, and ShellContent.
• FlyoutItem are for navigation patterns requiring a flyout menu.
• TabBar is for navigation with bottom tabs and does not require a flyout.
• Tab represents grouped content navigable by bottom tabs.
• ShellContent signifies the ContentPage objects for each tab.
• These objects manage the structure of the app's presentation.

Pages

• Pages are the foundation of the UI hierarchy within a .NET MAUI Shell application.
• The MainPage class, derived from ContentPage, is the basic page type, displaying a single view.
• TabbedPage serves as the root page for tab-based navigation, containing child page objects for each tab.
• FlyoutPage implements a master/detail presentation, with a list of items in the flyout and detailed views appearing upon selection.
• NavigationPage enables hierarchical navigation, allowing users to move forward and backward through pages

Views

• A content page displays a view, enabling users to retrieve and present data.
• ContentView is the default view which displays items as-is, and items may disappear if the view is shrunk until it is resized.
• ScrollView displays items in a scrollable window.
• CarouselView provides a scrollable view for swiping through a collection of items.
• CollectionView retrieves data and presents each item using a template.

Controls and Layouts

• A view can contain a single control like a button, label, or text box, and views themselves are also controls enabling nesting.
• Controls are positioned using layouts.
• Layouts defines the rules for displaying controls relative to each other and can be added to a view.
• The VerticalStackLayout element is a control for fine-tuning the layout of other controls.

Common Layout Controls

• VerticalStackLayout and HorizontalStackLayout are stack layouts.
• They arranges controls in a top-to-bottom or left-to-right stack.
• StackLayout has a StackOrientation property that can be set to Horizontal or Vertical and dynamically adjusts the display when the device is rotated.
• AbsoluteLayout sets precise coordinates for controls.
• FlexLayout wraps child controls and adapts to screen sizes, offering alignment options and even spacing.
• Grid positions child elements in rows and columns, with customizable sizes and spans.

Tuning a Layout

• Margin controls space around the outside of a control.
• Padding keeps children away from the border of a layout.
• Spacing adjusts the whitespace between children in VerticalStackLayout or HorizontalStackLayout, adding to the control's margin.