Xamarin Free For All!

Yesterday Microsoft announced that the Xamarin platform (the ability to run C# apps on iOS and Android) would be free with all versions of Visual Studio 2015 Update 2. This is great news and takes away a barrier for developers to use their .NET skills to write cross-platform apps.

We’ve had a number of free libraries for Xamarin for a while so I just wanted to post a quick reminder:-

Charming Apps – Provides consistent UWP style APIs you can call across iOS, Android and Windows platforms for many common tasks. From reading the app manifest properties at runtime through to UI elements and integration with platform functions like SMS, Email etc.

Xamarin Forms Maps Windows Renderers – Currently Xamarin Forms Maps only has renderers for iOS, Android and Windows Phone Silverlight. This package adds renderers for WinRT and UWP platforms.

Device Picker – Currently only supporting Windows platforms this adds a UWP style device picker to Windows Phone 8.1 and Windows 8.1 projects.

We’re continuing to extend the Charming apps libraries and will monitor as Xamarin Forms evolves…

UWP and XAML CustomResource Markup

UWP doesn’t support writing custom markup extensions however there is one built in markup extension which is extensible. The CustomResource extension allows you to write XAML such as:-

<TextBlock Text="{CustomResource PortableStringResource1}"/>

In this case PortableStringResource1 is a unique key to refer to a resource in a source of your choosing. There is no out of the box implementation so you need to create your own class which derives from Windows.UI.Xaml.Resources.CustomXamlResourceLoader and provide an implementation of GetResource. Then in code which runs during your app start-up you create a new instance of your custom class and assign it to CustomXamlResourceLoader.Current. Then all requests are passed to your code to be resolved.

One place you may want to use this is where you are getting string resources from a different source than the modern resource system. In a pure UWP approach you can set an x:Uid for a XAML control then add string resources of the form MyId.SomeProperty to set the specified property from the resource. Another place you might have resources defined might be in a Portable Class Library. Because these work across multiple projects you might have string resources specified in a .resx file which you use with a number of projects (think Xamarin etc) and you may wish to also use these from a UWP client. Because of the way these resources are built into the UWP project you can access them via a Windows.ApplicationModel.Resources.ResourceLoader provided you specify the name of the resource set. This is the full namespace and classname of the generated class in the PCL. For example if your PCL has a base namespace of PortableClassLibrary and you have a resx file called StringResources.resx this is “PortableClassLibrary.StringResources”.

For the platforms where it is supported I’ve added a WindowsXamlResourceLoader class to InTheHand.UI. This can be used to refer to either resources defined in the UWP application resw or a named resource set in a referenced library. The source can be found here:-

https://github.com/inthehand/Charming/blob/master/Source/InTheHand/UI/Xaml/Resources/WindowsXamlResourceLoader.cs

An example of setting up the resource loader is called in the App.xaml.cs App() constructor:-

Windows.UI.Xaml.Resources.CustomXamlResourceLoader.Current = new InTheHand.UI.Xaml.Resources.WindowsXamlResourceLoader(typeof(PortableClassLibrary.StringResources).FullName);

The sample project for this blog contains the UwpClientApp and PortableClassLibrary projects to demonstrate the complete solution.

This is just one example of harnessing the CustomResource markup extension for your own use. You could write a resource loader to return values from any other source, you supply the glue to hook it together. The only limitation is you can’t really change the resource loader while dipping in and out of parts of your app so you need just one implementation. You could work around this by prefixing the key with different values linked to different sources…

Xamarin Forms Windows Colours

When you work with custom renderers on Xamarin Forms (and it’s very difficult not to!) you often have to convert from Xamarin Forms types to their native platform equivalent. In the iOS and Android implementations Xamarin include some extension methods to easily convert Color to the native equivalent. Being the Cinderella of the Xamarin Forms platforms Windows platforms have missed out on this so I’ve filled the gap with this handy extension method:-

https://gist.github.com/peterfoot/be89d5b3c5ac4cc16ae1

This works for Windows Phone 8.1, Windows Store and UWP targets (sorry I haven’t created the Silverlight equivalent)

WebAuthenticationBroker Hints

Anyone who has tried to use the WebAuthenticationBroker beyond the simplest of scenarios has probably run into problems and sometimes all you want is a good descriptive error message. Getting things setup just right often takes a certain amount of trial and error so I’m documenting a few things here which are the results of a certain amount of trial and a considerable amount of error. This is as much a reminder for myself the next time I try and do this as it is (hopefully) some useful extra information for you.

Single Sign-in

If you can get the stars to align correctly, your OAuth endpoint can perform single sign-in on a corporate network. If you read the documentation you’ll see you have to specify the flag WebAuthenticationOptions.UseCorporateNetwork when you call AuthenticateAsync. This can be confusing because this flag isn’t needed when debugging when your app is given Intranet access automatically. To set this flag you also need to specify Enterprise Authentication, Private Networks and Shared User Certificates capabilities in your application manifest. Once you’ve added these you can’t submit the app through the public Windows Store.

A caveat to this is that you can only do single sign-in if your “web” application is setup with a redirect Uri which is the app package identity and you use the overload of AuthenticateAsync which doesn’t take a redirect Uri. This is the Uri returned from a call to Windows.Security.Authentication.Web.WebAuthenticationBroker.GetCurrentApplicationCallbackUri() at runtime. This identity will change between a side-loaded developer signed package and one which has been distributed through the Windows Store or a private company portal.

Error Codes

A lot of errors within the WebAuthenticationBroker process will result in a return status of WebAuthenticationStatus.UserCancel. However this is not always because the user has explicitly cancelled the process. The ResponseErrorDetail property returns an error code to give the reason and here are some possible values:-

0x800c0019 – An SSL failure. A common cause of this is that the clock is not set correctly on your phone/PC and it can often occur when your device battery went flat and it reset itself to some default date in 2014 and you’ve forgotten to correct it.

0x800c0005 – Network connection error. This is probably because you have no mobile signal and no WiFi.

This isn’t an exhaustive list but knowing the common error codes allows you to write a descriptive message for the user to hopefully resolve the problem themselves.

InTheHand.UI v9.0

I’ve updated InTheHand on NuGet and added the accompanying library containing UI functionality (InTheHand.UI). The main shared piece of functionality here is the MessageDialog (ala Windows.UI.Popups) and this works across all the Windows platforms (Including Windows Phone Silverlight) and iOS and Android. The appearance of the dialog is as the native experience with one exception…

MessageDialog.UWP.Native

We noticed on Windows 10 that the appearance of MessageDialog changed for our 8.1 app, rather than being a band across the width of the screen it was now a true floating window in its own right but this had one negative aspect – the title text appeared twice on the dialog. Users reported this as confusing and there is currently no workaround directly. In UWP apps there is now a ContentDialog control which is used for popping up content with up to two action buttons (you may recall this from Windows Phone 8.1) and so our implementation wraps this API on Windows 10 Desktop while exposing a single MessageDialog API. To avoid breaking the API we currently fall back to the system MessageDialog if you use three Commands. You can see a taste of the various flavours below:-

MessageDialog.Montage

The other functionality within InTheHand.UI is currently specific to Windows flavours and I’ll be discussing it in a future post.

Build Charming Apps v9.0 Preview

With the impending release of Windows 10 I set about updating the Charming Apps libraries to support UWP targets and it soon became painfully clear that things had got too complicated. There was a separate dll for each small area of functionality and various dependencies and 17 NuGet packages to manage (each with multiple platforms).

Version 9 is a reboot of the project and currently consists of just two packages – InTheHand.dll and InTheHand.UI.dll. The first of these is now live on NuGet in preview form and replaces a number of old libraries and adds new stuff! During the MVP Summit I was able to spend the Hackathon rebuilding my development environment and refactoring the entire solution.

https://www.nuget.org/packages/InTheHand/

The API follows the UWP model where possible, making it familiar to Windows developers while extending both backwards to prior Windows versions and also sideways to Xamarin platforms. Also new in Version 9 is a PCL build which allows you to call the shared functionality from a PCL with the functionality itself provided by the platform specific dll in the consuming application. This is useful in scenarios such as Xamarin Forms projects.

For example InTheHand.ApplicationModel.Package provides a mechanism to query the current application package for name/version etc. This is the sort of information you might need for a custom About page or to pass to analytics etc. The InTheHand.ApplicationModel.DataTransfer namespace contains Clipboard and Sharing functionality which now supports Android and iOS too invoking the native experiences in each. The remainder of the InTheHand.ApplicationModel namespaces allow you to kick off a number of tasks such as SMS, Email etc. Other namespaces exist for querying display properties and battery state.

All the code is on GitHub and a very rudimentary version of documentation is in the project Wiki. Most of the documentation in CodePlex still applies too and will be migrated in due course.

https://github.com/inthehand/Charming

Coming in the InTheHand.UI package are InTheHand.UI.Popups (MessageDialog) and InTheHand.UI.ApplicationSettings (currently Windows platforms only) both of which have some neat Windows 10 specific tweaks.