Intro to Uno Platform: Full C# Cross-Platform Development

What Is Uno Platform?

Tim opens the video by summarizing Uno’s mission: “Build once and deploy everywhere — that’s the dream, and the Uno Platform makes that dream a reality.”

Uno is more than just a framework or toolkit. As Tim explains, “This is a complete platform,” enabling developers to create cross platform applications from a single codebase. Uno supports Windows, Android, iOS, Linux, macOS, and WebAssembly, allowing one project to reach every major environment — from desktops to mobile devices and even the web.

Tim addresses cost right away. He assures viewers that Uno is a free, open source project under the Apache 2.0 license: “Everything you need to build and deploy your application is all free.” The core platform is completely free for all users — individuals, small teams, and even large companies.

The only paid tool is Hot Design, a UI designer that speeds up app building, but it’s optional. Uno’s sustainability model, Tim notes, follows something like Red Hat’s: advanced premium tools and enterprise support fund the open source foundation.

Installing Uno in Visual Studio

Tim walks through installing Uno in Visual Studio. He heads to the Extensions menu, searches for “Uno Platform,” and installs it.

He explains why this installer matters: “Cross platform development is not easy,” he says. Creating apps for Android, iOS, Windows, Linux, and the web means wrangling different SDKs, emulators, and deployment systems. Uno simplifies the messy parts:

“This installer has done a great job at doing that for you,” Tim says, because it also sets up required components like .NET MAUI, emulators, and tooling behind the scenes.

Creating a New Uno Project

With Uno installed, Tim starts a project in Visual Studio: File > New Project > Uno Platform App. He names it “UnoDemo,” then points out an important setup step:

“You need to check this box — ‘Place solution and project in the same directory’ — or you’ll get an error.”

From there, Uno launches its powerful Project Wizard, which Tim calls “amazing.”

Exploring the Project Wizard

Tim spends time on the wizard because it’s where cross platform developers customize the foundation of their apps.

First Run and Environment Setup

When Tim clicks Create, the project builds, and Visual Studio flags environment issues. That’s where Uno’s Uno Check tool shines.

“Copy this command, run it, and keep running it until it doesn’t find any more errors. It’ll fix what it can.”

Uno Check handles installing SDKs, configuring Android Studio, and setting up emulators. Tim praises this automation:

“There’s a lot of complexity here — and they take all that complexity and clean it up.”

Running the App and Using Hot Reload

Tim switches to the desktop target (fastest for testing) and runs the app. The generated demo has a text box and button — simple but functional.

He demonstrates Hot Reload — the free feature that lets you change UI code in XAML and instantly see updates:

“I changed ‘Enter your name’ to ‘Enter your given name,’ hit save, and there it is live.”

This seamless workflow is a major productivity boost for cross platform developers working across multiple platforms.

Exploring Hot Design – Optional but Powerful

Next, Tim clicks the flame icon — enabling Hot Design.

“This is the paid upgrade — you don’t have to have it, but it’s nice to have.”

Hot Design allows you to drag and drop UI elements onto a running app, tweak their properties, and have those edits reflected directly in the source code.

Tim drags in a TextBlock, sets it to say “Hello World,” and changes its color. He points out:

“Hot Design doesn’t just preview — it modifies your actual code.”

He also demonstrates how Hot Design handles responsive layouts for mobile devices, light/dark theme switching, and advanced binding setups — all while the project is running.

Tim sums up the value:

“If it saves even an hour a month, it’s worth $39. It’s going to save more than that.”

Looking at the Generated Source Code

Tim inspects the code Uno generated. He shows how the project is based on MVUX, with models bound to pages, and highlights:

• Services folder – includes caching and HTTP sample code.

• Localization resources – translation samples for English, Spanish, French, and Portuguese.

• csproj differences – Uno uses its own UNO.SDK instead of Microsoft’s default.

Tim shares a developer tip: during debugging, you can comment out all but the desktop target to speed up rebuilds.

Understanding Platforms and Custom Code

Tim explores the Platforms folder, which contains platform-specific code for Android, iOS, and more:

“For the most part your code will work across platforms, but there are certain things you’ll need to write just for Android or iOS — and those go here.”

This flexibility means Uno handles 95% of the cross platform work, while still letting you write source code tailored to unique mobile devices or embedded devices when needed.

Beyond Visual Studio – VS Code and Rider

Uno isn’t locked to Visual Studio. Tim shows how cross platform developers can use VS Code or JetBrains Rider, thanks to Uno’s web-based project wizard at new.platform.uno.

“You can configure a project there, generate a CLI command, and scaffold the same starter project outside Visual Studio.”

This makes Uno flexible for developers working on all kinds of setups — from hobbyists experimenting on Linux laptops to teams building production mobile applications on Windows machines.

Wrapping Up: A Platform That Truly Spans Everywhere

Tim wraps the video by summarizing Uno’s reach:

“It deploys to Windows, Mac, Linux, WebAssembly, iOS, and Android. Your C# code runs pretty much anywhere.”

Uno allows developers to write apps with a single codebase and run them across multiple platforms — from mobile apps on iOS and Android, to desktop software on Windows and Linux, to web applications in the browser.

Tim encourages everyone to try Uno and share what they’d like to see explored next: “There’s so much to dive into that I can’t wait to show you all.”