During Build’s 2017 day 2 keynote, Microsoft’s Terry Myerson spoke about the new Xamarin Live Player (XLP). As we wrote then, XLP is "…a new technology designed to make it easier for developers to write apps for iOS and Android devices." Xamarin’s Joseph Hill has since provided some additional details about this technology.
The main benefit of using XLP is that it makes it possible for a developer to start building a mobile app for iOS or Android without first having to download the corresponding SDKs for those platforms. Simply start writing up a mobile app, and deploy it to your iOS or Android device for real-time development and debugging. Used in conjunction with Visual Studio, changes can be made and ideas explored quickly. Think of it as a way to begin building a rapid prototype that is a precursor to, but not replacement for, the SDKs and tools normally used to build a complete mobile app. Once you have established the viability of your concept and design, the project files used with XLP can be carried forward into the full-fledged development cycle.
When your app grows and is ready to add extended features like a launch screen, app extensions, or widgets, it will then be necessary to install the full Xamarin development environment appropriate for your targeted devices. This means that XLP doesn’t eliminate the complete need for a Mac-based development environment if you are a Windows user, it just means you delay this need. This is especially useful if a developer just wants to prototype the viability of an app before committing full resources to it.
At present, the focus of XLP is on Xamarin.Forms applications which support C#, F#, and XAML. There is some limited support for iOS storyboards, but editing these does require the use of a Mac.
To try XLP on your own, you will need a copy of Visual Studio 2017 Preview (15.3+ release) or Visual Studio for Mac on your development machine. Then visit the app store appropriate to your iOS / Android device and install the Xamarin Live Player. Once your development machine has paired with your device, you can get started. Note that a remote server is used for the initial pairing, but your app code is not sent to this 3rd party server.
Xamarin has prepared a list of current limitations which they will keep updated as corrections are made as well as a guide for getting XLP support enabled on your development machine.