Modern apps tends to use complex designs and need to adapt to the growing number of device sizes and form-factors. Building UI's has always been a hard job. Is a mac the best machine Is it a pc laptop plus a MacBook Is it better to have a lot of processing power to reduce compiling, Just installed latest version of VS2019 (v16.1.5)The Android Emulator can be run in a variety of configurations to simulate different devices. Each configuration is called a virtual device. When you deploy and test your app on the emulator, you select a pre-configured or custom virtual device that simulates a physical Android device such as a Nexus or Pixel phone.Noted also that I got a different version of the nuget packages Xamarin.Essentials (1.1.0) and Xamarin.Forms (4.77)By installing the app on both Android and iOS simulators and real test devices, they will see how the UI renders as native controls on each platform.
App Does Not Show Up On Android Emulator Xamarin Trial And ErrorXAML Hot Reload: allows us to make changes to change XAML code and have it updated on a running instance of your app, either on a simulator or a real device. Lucky as Xamarin.Forms developers, we have some great tools to facilitate this jobs: Commonly you do several roundtrips between edits to test every dynamic and interactive aspect of the interface. As developers we think of UI elements as dynamic components and interactive components.Writing a complex UI is for the most part a trial and error exercise. Drawing UI from an application framework is not like composing it on a tool like Photoshop by drawing and styling primitives (although its possible through shapes). This allows developers to have full control over the rendering of the interface and split it into reusable components, but comes with drawbacks.Its hard to write UI code without seeing its actual output.![]() Let's give it a try! Open Visual Studio and create a new Blank Xamarin.Forms project. Using Hot ReloadIf you've updated to the latest versions of Visual Studio and are working on new projects, Hot Reload is mostly "there". Hot Reload allows us to avoid the expensive roundtrip of building and deploying the app to test UI tweaks, lettings us preview it directly on a device (which is the best method for testing our UI work).As changes made to XAML files are instantly updated in the running app, in practice Hot Reload makes the simulator a kind of real-time previewer. It's not meant to be perfect, just to give us an entire new interface. Let's try to change the entire page layout, replace the inner of the ContentPage element with the following:This is a roughly and incomplete re-creation of the Interval Timer app main screen. You can keep doing changes to this file, and when you're happy with them just save it to have it deployed instantly to the running app. Save the file and see the "magic":After saving the file the page was refreshed with the changes you've made. Open the file on the editor while you keep the debugger running and let's change the header to a red background. After creation just run the app on the simulator.This is the design of the MainPage.xml from the Blank project template. There's a feature currently in preview to refresh only the changed view. It by no means represent real production code that I would add to a project.By default, Hot Reload will refresh the entire page no matter how simple is the change. Hot Reload is smart enough to identify custom views and keep them updated as you edit, which allows for example to change the layout of a Collection View cell on it's own cell file and having it updated on the running app.In the following example I've created a custom view to represent the control panel on the bottom of the screen (file Views/ControlPanel.xml):Try changing something on the nested view and see it being propagated to the simulator!Note: I've kept the code for the views as simple as possible to focus on previewer experience. □So, when you save the file, you should see that after a flash the whole content of the screen will be replaced in the running app.You can keep doing this until you're satisfied, then you get to your next design subject. We'll be covering it in a future post.XAML Hot Reload is available on Visual Studio for Mac and Windows starting on the free community tier. Here's the code:Notice we're using the Ellipse View from Shapes feature of Xamarin.Forms 5. Create a run configuration to start both projects on debug, now you can put the iOS simulator and the Android emulator side-by-side and review how your changes apply on both platforms:In the example above I've added the code for a Stop button to the right of the panel. Avast support for mac os x sierraIt was the first integrated tool to aid developer on designing Xamarin.Forms Pages and Views.The Previewer is available while editing XAML files. PreviewerThe XAML Previewer is a built-in tool in Visual Studio that shows a real-time representation of the XAML content that you're working on your main editor. Its available only to Android and iOS, and some scenarios will require rebuild and redeploy. This would open the tool for scenarios like C# Markup. Also I hope that they've come to support refreshing C# code also. There are some preview features like reloading only changed parts and stability improvements. I suppose they're laying the ground for MAUI that will more officially supported platforms out of the box.Hot Reload should evolve overtime. I'm personally sad about the discontinuation of the Previewer by its convenience, and Hot Reload should serve us pretty well when its gone. Then you can edit your code to have its preview updated in real time:The Previewer is a fine tool and it's been serving us well for some years, but now it's officially beeing phased out (check out the warning on its documentation page) in favor the XAML Hot Reload.Visual Studio is already suggesting using Hot Reload instead of the Previewer:XAML Previewer and Hot Reload are great tools to aid Xamarin.Forms developers on composing their UI's. During the last decade he taught several courses on mobile development on his home country and is passionate about learning and teaching technology.You can find him on GitHub github.com/ravero, LinkedIn linkedin.com/in/ravero and blogging on ravero.medium.com (in portuguese □).
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