Tutorial

Nick Randolph’s earlier post in this blog series covered the basics of sorting and grouping. The CollectionViewSource provides a wrapper around a data source that can indicate if the source is grouped and will maintain the selected item. Suppose you are familiar with CollectionViewSource from WPF. In that case, you may not be aware that the class no longer has functionality for sorting and grouping itself in UWP, but this can be achieved in the underlying source. The WinUI/Uno version follows the UWP functionality. CustomSorting Sample App Sorting Collections .NET has a set of functionalities for querying collections, and they make up the System.Linq namespace. This adds several extension methods to standard .NET collection classes to allow querying, sorting, and grouping. LINQ stands for Language INtegrated Query, a declarative query syntax right in your C# code. You can perform operations using the query syntax or directly using the fluent OrderBy, GroupBy, etc. methods provided. LINQ Fluent When you are using intrinsic types such as Int32 (aliased as “int” in C#), there is a predictable behavior for sorting because these types implement the IComparable<T> interface. This interface defines a single method CompareTo which returns a value indicating whether the other instance is less than,

WinUI contains classes for menus belonging to a Window and context menus attached to other controls. Users will be familiar with menus in traditional desktop applications and mobile devices. Unlike previous Windows APIs, the WinUI MenuBar and MenuBarItem do not support data binding, so you must build your menu tree from MenuFlyoutItem, MenuFlyoutSubItem, and MenuFlyoutSeparator, either in code or directly in your XAML.  The two types of items cover all the menu scenarios since the MenuFlyoutSubItem can contain additional menu items. A static menu might look something like this: Data-Bindings Menu Sometimes, you may want to populate a menu dynamically from a data source rather than hard-coding them. In this case, there is a little more work to achieve the desired results. There are a couple of ways you could present a grouped collection in a menu – you could choose to display each group using a MenuFlyoutSubItem and have the items nested below this.   While technically, you can continue to nest multiple levels with the MenuFlyoutSubItem, in practice, more than two layers become challenging to navigate, especially on smaller screens. Given a single-level grouped collection, you can write code like the following to populate a top-level MenuBarItem from the

XAML platforms, from WPF and Silverlight to Uno and WinUI, support the MVVM pattern by separating the View described declaratively in a XML dialect with the application logic in code. The VM in the name represents the View Model; this is the code responsible for exposing functionality to which the View can bind without having any knowledge of the View itself. In addition, the platform provides data-binding functionality allowing the View to dynamically display data from the View Model and react to changes.   By declaring namespaces in your XAML file, you can declaratively use a surprising amount of your code and logic beyond the platform’s controls and components. In addition, some limitations with the code can be referred to from XAML – any class must have a default constructor, controls bound to a DataContext must bind to Properties on that source, or in the case of action items like Buttons, an ICommand.  However, in the modern XAML found in Uno and WinUI, there is an additional markup extension called x:Bind, which goes beyond the basic support for binding found in all previous XAML flavors.  By the end of this tutorial or following the sample code, you will have learned when