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Code and slides posted for my latest talks

.NET, Conferences, HoloLens, MVVM, Technical stuff, Universal Windows Platform UWP, UX, Windows 10, Work, Xamarin, XAML
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October and November have been quite busy with travel. I talked at a few occasions in some cool events and want to take a moment to share the code and slides below:

Xamarin Dev Day, Zurich, Switzerland

I love the concept of the Xamarin Dev Day. It’s a great way to reach out to local communities and have a day of fun teaching and training with Xamarin content. This year I took part to the Zurich, Switzerland occurrence. It definitely didn’t hurt that it was help in a very cool space, under a train viaduct in the previously industrial area of the city, which is these days a pretty cool place to live and work.

I held my talk titled “Building truly cross platform applications with Windows, Xamarin and MVVM Light” which comments on the fact that the so called “UWP” (Universal Windows Platform) applications are only for Windows (hence the W) and that if you want to target mobile iOS and Android devices, you need something more. Xamarin and MVVM Light are great solutions in this scenario, because they maximize the amount of code that can be shared, all the while increasing the testable surface of the application. You can find the code and slides at this page.

KC .NET User Group & Xamarin KC Dev, Kansas City, Missouri

You might have read that the company I joined in 2008 (IdentityMine) was acquired this year by a company based in Kansas City named Valorem Consulting. On November 1st and 2nd, I spent time at the head office to meet with a maximum of new colleagues. It was a nice stay in a city (and state) I had never visited before. In fact I even “visited” two states during that stay, because Kansas City is laid over Missouri and Kansas! Earlier on I had tweeted about me visiting KC, and the local .NET developer user group contacted me and asked if I wanted to speak at a user group meeting on that evening. Of course the answer was a resounding yes! And the best part is that the Xamarin KC user group also joined the fun for their first ever joint event. We had a great attendance with a full room of about 65 people, and a very nice interaction. After the event, a small group gathered at a local bar and we had pie and drinks (I had a root beer float, because why not). Excellent way to make new friends in a new city! I also held my talk “Building Truly Universal Applications with Windows, Xamarin and MVVM Light”.  You can find the slides and code here.

DevIntersection Europe, Haarlem, The Netherlands

Right after my return from the US (with the visit to Kansas City, a few days in the office in Seattle and then the MVP and Regional Directors Summit in Bellevue/Redmond), I had another short trip to the Netherlands. I spoke at the DevIntersection conference in Haarlem, a small city not far from Amsterdam. The location was superb, a convention center close to the historical center of the city, the hotel was great too (though the bed was wayyyyy too soft for me :) and the audience was very nice. It is definitely smaller than DevIntersection in the US (where they have events in Vegas and Orlando), but I had a good albeit small audience nonetheless and some great interactions with attendees and fellow speakers.

I spoke about the Windows 10 Universal Windows Platform, a dense session which contains information about creating a new UWP app; adapting the user interface to the various form factors, resolutions, orientations etc; porting classic windows applications to the Windows 10 ecosystem with the Desktop App Converter (also known as Centennial bridge); the Windows Continuum; and Microsoft HoloLens. Unfortunately because of unknown technical issues, I was not able to stream the HoloLens output to my phone nor to my Surface like I used to do. Unfortunately we ran out of time before I was able to solve the issue (which would probably have required restarting the HoloLens and the phone). I want to apologize to the audience for this technical glitch. I hope that the people who joined me later for a quick trial of the HoloLens were happy anyway, and that the others didn’t go back home with a bad image of this amazing technology :) I recorded a few videos showing the various demos I wanted to give, you can find all the material including code and slides on this page.

Thanks all for attending and happy coding!

GalaSoft Laurent Bugnion
Laurent Bugnion (GalaSoft)
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#Microsoft #Experiences in Paris: Code and slides

.NET, Conferences, HoloLens, MVVM, Technical stuff, Windows 10, Work, WPF, Xamarin, XAML
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Last week I had the pleasure of taking the TGV from Zurich to Paris, and after a quick 4 hours of comfortable travel, to make my way to the Porte Maillot and the Palais des Congrès.

TL;DR: All slides and source code is available from here.

A podcast

After a good night sleep I made my way to the speakers lounge and prepared the last steps for my talk. Then I took a moment to head to the meeting room where the Live Tiles podcast was being recorded. A band of podcasters got together and talked about the future of Microsoft. It was so nice to “see these familiar voices” in action. Even nicer when Christophe (Toss .NET) and Denis saw me and pulled me in to talk about HoloLens and our experiences with this device. You can hear the recording here, my contribution starts at 36:30.

My talk: Really universal apps with Xamarin and MVVM Light

My talk was titled (in French) “Construisons des applications vraiment universelles avec Windows, Xamarin and MVVM Light”. This favorite topic of mine shows how you can structure an application to share a maximum of code without any compromises. You can build healthy layers of Model and ViewModel, unit test them so you can feel secure about not breaking anything with future changes. Then you can build a thin layer of real native user interface for any supported framework with XAML or Xamarin (Windows Presentation Foundation, Windows 10 Universal, Xamarin.iOS, Xamarin.Android). And if you are in an enterprise scenario and looking for maximum productivity, you can also of course use Xamarin.Forms and render the same UI to all supported platforms.

The MVVM Light Toolkit assists you in these tasks, notably by providing a Data Binding framework for Xamarin.iOS and Xamarin.Android, as well as components that make it very easy to connect a list control to an ObservableCollection, with automatic refresh in case the collection changes. This open source toolkit is in it’s version 5.3, has been downloaded almost 1.7 million times and is even used by Microsoft to build parts of Windows 10.

I was really pleased when I headed to my conference room and saw a long queue in front of the entrance. I gave my talk to a standing room of about 270 people, and loved the interaction during and after the talk. A lot of very positive feedback, and we stayed and talked until the hostess kicked us out of the room :)

Thank you to everyone who came and made this a memorable moment. You will find all the details of the talk, the slides and the source code from this portal.

Some tea

Before I made my way to the Palais des Congrès, I took a pit stop at one of the most wonderful shops on Earth: the Mariage Frères tea store. This old fashioned store is stock full of amazing teas from all over the world. It’s a must-visit if you are a tea enthusiast or if you just want to spend a moment living in an atmosphere of luxury and pleasure.

GalaSoft Laurent Bugnion
Laurent Bugnion (GalaSoft)
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Slides and code samples for VS Live Redmond

HoloLens, MVVM, Technical stuff, Universal Windows Platform UWP, VSLive, Windows 10, Work, WPF, Xamarin, XAML
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VS Live just took place in Redmond, and I had a great time. I had three sessions in one day, and I was really exhausted in the evening, but it was absolutely worth it. Speaking in Building 33 (the conference center on Microsoft campus) was an amazing experience. I have spent so many hours in this building, listening to amazing speakers of Microsoft and others, during MVP summits and other events… so really it was quite magical to be on the speaker side this time, in room St Helens.


Thanks to every one who came to my talks! I hope it was informative and useful, and that it encourages you to try those technologies and techniques.

Here are the pages for the talks I gave:

Windows Presentation Foundation (WPF) 4.6
Windows Presentation Foundation is what people are using to build real applications for the enterprise, the industry, the workplace, and for every situation where Windows 10 Universal isn’t quite ready yet. Far from being dead, WPF is 10 years old this year, and it’s still alive and kicking. It gives Universal Applications a run for their money. In this session, you’ll learn what is new in Windows Presentation Foundation, where it’s going in the future, and what you can achieve with WPF that Universal Application developers can only dream of. We’ll also see how these two roads cross and how existing WPF applications can be brought to Windows 10 using the Centennial bridge. Finally we’ll discover new features and tools recently implemented for WPF developers.

Windows 10 – The Universal Application: One App To Rule Them All?
Windows 10 and the Universal Windows Platform offer a lot of productivity and flexibility around targeting the broad set of devices that run Windows. As a developer, you have a lot of choice–from building a single binary that is identical on all devices, through to an app that adapts to the type of device and on to the point of building an entirely different app for each class of device. What’s the right thing to do? How should you think about building the “One App to Rule Them All?” What are the design and implementation trade-offs you need to consider? This session dives into these areas with a hands-on approach and shows what it really means to be building apps across families of Windows devices that have different capabilities. We will also talk about bridges (and especially the iOS Bridge to Windows 10), and new platforms such as Continuum and HoloLens (with live demos).

Building Truly Universal Applications with Windows 10, Xamarin and MVVM
With Windows 10 supporting an unprecedented number of platforms and form factors (from IOT to phones to tablets to laptops and desktops to XBOX and SurfaceHub, and even the new HoloGraphic computer HoloLens), the name ‘Windows 10 Universal application’ is fairly accurate. But to be honest, shouldn’t a truly Universal application run on Windows 7, iOS and Android devices too? Thankfully, this is possible thanks to a clever architecture pattern named Model-View-ViewModel, the .NET portable class libraries and the Xamarin frameworks. With these tools, we can structure an application so that most of the code is shared across all the platforms, and then build truly native UI that adapts without any compromises to the device it runs on. In this session, we will understand exactly how such universal applications are built. Laurent Bugnion, a XAML/C# expert, Microsoft and Xamarin MVP who started making universal applications before it was even a thing, will show you practical knowledge with a lot of demos. Come listen from the creator of the popular MVVM Light Toolkit how this powerful but simple library can be leveraged to help you target more users than you ever dreamed of!

Happy coding!

GalaSoft Laurent Bugnion
Laurent Bugnion (GalaSoft)
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Slides and sample code for #XamarinEvolve and #Techorama

.NET, MVVM, Techorama, WPF, Xamarin, XAML

These past weeks have been busy with travel and speaking. After the wonderful time in San Francisco for Build 2016, I had a few precious weeks to prepare for Xamarin Evolve (Orlando, FL) and Techorama (Mechelen, Belgium). I just came back and here is the time to post the slides, sample code, and for Xamarin Evolve we even have a video of the talk!

Xamarin Evolve


Evolve took place in tropical Orlando, and it was pretty nice to see sun, warm temperature and even some pool time on the day after the conference ended. I had a great time there. I talked about the DataBinding system in MVVM Light, which applies to Xamarin.iOS and Xamarin.Android. This critical part of all MVVM applications is there to ensure the connection between the ViewModel layer (typically in a portable class library and shared across all platforms) and the View layer. In Xamarin.Forms and on Windows, we don’t need an external databinding framework because we already have these (this is what you use when you write Text=”{Binding MyProperty}” in XAML). But in Android and iOS, there is no such concept, and this is where the MVVM Light platform-specific extensions come handy.

Here is the abstract (which was modified by Xamarin themselves… I normally don’t really use this marketing-y tone ;):

An In-Depth Study of the MVVM Light Databinding System

Living in the dark ages and still wiring up properties manually between your user interface and data source? Databinding is a technique to automatically synchronize a user interface with it’s data source and can vastly simplify how your app displays and interacts with data. While databinding is available out of the box for Xamarin.Forms and Windows applications, additional components are needed in Xamarin.Android and Xamarin.iOS. In this session, learn how to leverage databinding in your cross-platform applications as you master MVVM Light databinding and the MVVM pattern.

I created a page for this presentation on my website. There you will find the slides, video recording as well as the sample code.

Note: At the moment, some of the Xamarin Evolve videos are not working properly. Xamarin is informed. Thanks for your patience.



Techorama is one of my favorite conferences, created by the community for the community after the cancellation of TechDays Belgium. Gill, Pieter and Kevin created a hell of a show, which grew to host more than 1000 visitors these days. The venue is awesome too, it is a movie theater and we get to project our slides and code on a huge screen. This year there were quite a few renowned speakers from the US and the whole world in fact. Even though I got to spend only one night at home after coming back from Orlando before flying again, which was quite tiring and a bit stressful, I was really looking forward to go to Mechelen. I hope you enjoyed my session there about WPF. It was a fun session where I talked about the differences between WPF and the Windows 10 Universal platform, about new development in WPF (especially tools such as the Visual Tree, the Live Property Explorer, and XAML Edit and Continue), about the Windows Bridge “Project Centennial” which takes a classic Windows app and “packs” it to transform it into a Universal application. We finished with an exciting demo of a new feature shown at Xamarin Evolve the week before: the Xamarin Workbooks, which allow you to create a rich document (using Markdown) with titles, subtitles, images etc, and allows including snippets of C# that will be executed by the Xamarin Inspector tool. Because the tool supports Android, iOS and WPF, it was a great find and it fitted well in my session which aimed to show that WPF is still very current and state of the art. So I happily changed my presentation to include it in the demos.

Windows Presentation Foundation (WPF) 4.6

Windows Presentation Foundation is what people are using to build real applications for the enterprise, the industry, the workplace, and for every situation where Windows 10 Universal is not quite ready yet. Far from being dead, WPF is 10 years old this year, alive and kicking, and gives Universal Applications a run for their money! In this session, Laurent Bugnion, a Microsoft Windows Developer MVP and Microsoft Regional Director, WPF expert since 2006, will show you what is new in Windows Presentation Foundation, where it is going in the future, and what you can achieve with WPF that Universal Application developers can only dream of.

The presentation’s page is on my website, and will give you access to the slides and the demo source code. Make sure to check the last couple of slides for more resources!

One more thing

I recently discovered (not sure how I missed that) that my session about Windows 10 UWP at the Future Decoded conference in London last year had been recorded. I added the video to the presentation’s page. So in case you want to know how to adapt your UWP app on multiple platforms, this is where you can go!

Happy coding!

GalaSoft Laurent Bugnion
Laurent Bugnion (GalaSoft)

Releasing MVVM Light V5.3 to Nuget

.NET, MVVM, Work, Xamarin, XAML

With Xamarin Evolve coming up (I am currently on the way to Orlando!), it was time to release a new version and take care of a few bugs, improvements and new features.

Update: To be clear I didn’t remove the Windows 8.1 version, it is still available! Only the Windows 8 version is removed.

In version 5.3, the majority of the activity was on the data binding system for Xamarin.iOS and Xamarin.Android, with many improvements in stability and performance, as well as a few new features. Existing code will continue to work as is, and at most you might have a few “deprecated” warnings, which will give you time to update your code. I also added 3 classes and a few helpers around them, which should help you greatly when you work with lists: ObservableRecyclerAdapter (for Android RecyclerView), ObservableTableViewSource (for iOS TableView) and ObservableCollectionViewSource (for iOS CollectionView). These objects will be detailed in separate blog posts.

In other areas not directly Xamarin-related, you will also find quite a few bug fixes. Here is list of changes. You will also find a few explanations below. I will publish additional blog posts with more details about the Observable list components mentioned above.

Removed old frameworks

In a desire of simplification, I removed the Silverlight 4, Windows Phone 7.1 and Windows 8 versions of MVVM Light from the repo. This does NOT affect the Silverlight 5, Windows Phone 8.0 and 8.1, Windows 8.1 as well as Windows 10 of course which are still very well supported. The main reason for not supporting these older versions is that they require Visual Studio 2012 and cannot be maintained or tested in VS2015. I hope that this doesn’t affect your projects too much. Should that be the case, please send me a note. We can always find a solution!

Fixing Nuget install.ps1 and documentation

There was a silly bug in the install.ps1 script that is run after the Nuget installation is performed, it is fixed now. Also, I added a more explicit description of the packages mvvmlight and mvvmlightlibs, in order to underline the differences between both.

Documentation: Closures not supported

In the same vein, I added explicit documentation warning that closures are not supported in the Messenger Register method, as well as in the RelayCommand Execute and CanExecute delegates. This is sometimes an issue. The reason is that these components are using WeakReference to avoid tight coupling with the objects using them. When we store the delegate that will be executed by the Messenger or respectively the RelayCommand, we store them as WeakAction instances. This causes the delegate to be “dehydrated” and stored as a MethodInfo. When we “rehydrate” the delegate, we notice that the closure has been lost, and the call fails. I am experimenting with ways to work around that limitation (i.e storing the delegates are actual Action or Func and not dehydrating them, which will of course cause a strong coupling to occur… but would be acceptable in some cases if the developer explicitly opts into this). For the moment, closures are not supported and the developer needs to find another way, for example storing the parameter in an attribute or a list of some kind.


I optimized the code a bit there and made it less redundant. I also made the RaisePropertyChanged methods public (was: protected) following a user’s request. This can make sense in certain scenarios when an external object wants to call this method on another VM.


Here too I fixed some bugs. I also added new features for iOS:

  • Navigating with an unconfigured key in iOS: In iOS, the key passed to the NavigateTo method is often the same value as the corresponding Storyboard ID set in the Storyboard designer for a given controller. Until V5.3, you had to configure the key for the NavigationService, which was often leading to code such as
    Nav.Configure(“SecondPage”, “SecondPage”);
    this didn’t quite make sense. As of V5.3, if you call NavigateTo with a key that is not configured, we will attempt to find a corresponding controller with this same Storyboard ID. Of course if you want to use a different ID, you can still configure the navigation service like before.
  • Retrieving parameter without deriving from ControllerBase: Until now, the implementation used to retrieve a navigation parameter from the NavigationService forced you to derive your controller from ControllerBase. That was annoying, especially in cases where you had to derive from another base class anyway. I removed this restriction. Instead, you can now retrieve the NavigationService from the ServiceLocator in the ViewDidLoad method, and then call the GetAndRemoveParameter method to get the navigation parameter (if there is one). This is the same method than in the Android NavigationService.

Binding system

I fixed a few bugs here which were causing the data binding to fail in certain scenarios. I also added a lot of unit tests to test current and new features (currently about 300 unit tests which run in both iOS and Android), as well as a few features. Expect samples very soon!

  • FallbackValue: This value can be set in the SetBinding method (or in the Binding constructor) and will be used in case an error occurs when the Binding is being resolved. This can happen, for example, if you have a complex path expression and one of the elements is null, which would cause a NullReferenceException to happen inside the Binding. This exception is caught and nothing happens in the application, but the FallbackValue will be used as the Binding value if the user has set it. This can be used for information purposes. For example, if your source property is MyViewModel.SelectedItem.Name, and nothing is selected, the SelectedItem is null and the FallbackValue (for instance “Nothing selected yet”) is used.
  • TargetNullValue: This value can also be set in the SetBinding method (or in the Binding constructor) and will be used in case the Binding value is null. This can also be used for information purposes.
  • SetCommand with static parameter: I added an overload to the SetCommand extension method which can be used to pass a static parameter to the ICommand’s Execute and CanExecute methods. Prior to V5.3, you had to define a binding for this (and use the SetCommand(…, Binding) method) which was very cumbersome in case the binding value never changed. Now you can use the SetCommand method with a simple value (or if you want to observe the value you can still use the SetCommand method with a binding).
  • SetCommand for ICommand: In previous versions, you could only use SetCommand with a RelayCommand (or RelayCommand<T>), which was an oversight. Now I modified this method to work with any ICommand.
  • New name for UpdateSourceTrigger: This method is now named ObserveSourceEvent. The old method is still available but marked as deprecated. The old name was confusing for users.
  • New name for UpdateTargetTrigger: Similarly, this method is now named ObserveTargetEvent. The old method is still available but marked as deprecated.
  • Binding with implicit event names: When you set a binding on a UI element in Android and iOS, you must also specify which event should be observed for changes. This is necessary because properties in these elements, unlike in Windows, aren’t depedency properties. For instance, you can choose between FocusChange or TextChanged for an EditText, etc. In the huge majority of cases however, the same event is used over and over for a given element.
    On Android, the TextChanged event is used for an EditText and the CheckedChange event for CheckBox; on iOS, the ValueChanged event is used for UISwitch, the Changed event for UITextView, and the EditingChanged for UITextField. Note that existing code does not need to be changed unless of course you want to simplify it. And like before, you can continue to use ObserveSourceEvent and ObserveTargetEvent (formerly UpdateSourceTrigger and UpdateTargetTrigger) to specify a different event if needed.
  • SetCommand with implicit event names: Like with the Binding class, when we set a Command on a control, we specify which event must be observed to trigger the command. For commonly used controls, this is mostly the same event. To simplify the code, you don’t have to explicitly specify these events anymore. The events that are observed implicitly are: On Android the Click event for Button, and the CheckedChange event for CheckBox. On iOS, the TouchUpInside event for UIButton, the Clicked event for UIBarButtonItem and the ValueChanged event for UISwitch. Of course you can also continue to specify these events explicitly, or any other event you wish to observe instead.
  • Binding to private fields and local variables: In previous versions, you could only set a binding on public properties (for example public MainViewModel Vm, or public CheckBox MyCheck; in V5.3, you can also set bindings on objects which are saved as private attributes. You can even create a new Binding (using the Binding constructor instead of the SetBinding method) on elements which are defined as local variables.
  • Binding on RecyclerView, TableViewSource and CollectionViewSource cells: The feature above (binding on local variables) can be useful, for example to create a new binding between a data item and the cell that represents it in a list control. I’ll have blog posts for RecyclerView, TableViewSource and CollectionViewSource.

As you can see, this is a massive change set and I am really happy that your excellent feedback has led to these improvements. Of course the task is not over and there is more coming. V5.3 should greatly improve working with data binding in MVVM Light, in Xamarin.iOS and Xamarin.Android. As always, keep your feedback coming!

For more information about data binding in Xamarin.iOS and Xamarin.Android, you can watch my Xamarin Evolve 2016 session (slides, sample code and video recording will be posted ASAP).

Happy coding!

GalaSoft Laurent Bugnion
Laurent Bugnion (GalaSoft)
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One million downloads!

MVVM, Technical stuff, Work, Xamarin, XAML

Logo MVVM Win8 Purple 103x80

I am not sure exactly when it happened but as I was reviewing the MVVM Light Toolkit’s download numbers, I suddenly realized that we are now over a MILLION downloads.

The breakdown of the downloads is as follows:

TOTAL: 1’130’704 downloads

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Source code and samples for the ADC15 talks

ADC, HoloLens, MVVM, Technical stuff, Windows 10, Work, Xamarin

I just published the material for last Monday’s Advanced Developer Conference in Frankenthal Germany.

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Upcoming speaking engagements and travels!

.NET, IdentityMine, MVVM, Technical stuff, Visual Studio, Windows 10, Work, WPF, Xamarin, XAML
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Wow it’s autumn already! When did that happen? The Summer was very busy, with a lot of super interesting work at IdentityMine, the release of MVVM Light V5.2, and preparation for an upcoming article in MSDN Magazine (more about that later) and even some work on some personal apps I wanted to port to Windows 10 and improve.

In the coming few weeks, I have some travel coming up, with speaking engagements. Here is the list below, and I will update it if something new comes up. I really hope to have a chance to see you at one of these talks, and if you do come, please come say hi and let’s chat!

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MVVM Light V5.2 is live!

.NET, Blend, MVVM, Technical stuff, Universal Windows Platform UWP, Windows 10, Xamarin, XAML

This week I published MVVM Light V5.2 to Nuget and to the Visual Studio Gallery.

There are a few highlights which are described as always in the Change Log. See further below for a more detailed explanation of some of the changes.

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#Techorama 2015: Slides and source code are online!

MicrosoftBand, MVVM, Technical stuff, Techorama, Work, Xamarin
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Techorama was a real pleasure. I have to admit I was a bit tired from all the travel (I had just come back from 2 weeks in the US a couple of days before flying to Brussels) but I was super happy to go because I know how well organized this conference is. They love their speakers, and we love them back.

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