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If you haven’t heard or dived into .Net Standard you are in for a treat. In short it provides a way to share code across platforms but in contrast to the PCL it gives you so many more platform specific features. For an in depth overview check out the official docs.

Note: If you are starting a new Project today with Visual Studio (VS) 2015.4, you will not be able to select .Net Standard by default. But the new templates for .Net Standard will be included in Visual Studio 15.5.

Creating the .Net Standard Class Library

Migrating an existing app to .Net Standard is pretty straight forward. Step one add a .Net Standard Library to replace your PCL project.

The VS Add New Project dialog, under Visual C# select Class Library (.Net Standard)

Migrating your source code

Then drag and drop all of your existing files from the PCL project to your .Net Standard library. Note that you don’t want to copy the packages.config or any of the files under properties.

CopyFiles

Now you can delete your PCL project that you have migrated. If you do so from Visual Studio note that the Project is still available in the file system. Which means you still have it if you forgot something, but also means that you will have to delete it later on if you want to remove it from the source control workspace.

Next step is to add all the NuGet packages you have used in the PCL project. If you are having trouble adding some of the packages look out for NuGet packages that are no longer needed due to .Net Standard support such as file system access. In other cases it could be because the NuGet package has not (hopefully yet) migrated to .Net Standard. In that case check out this post and don’t forget to ask the maintainers of the project when the project will be available for .Net Standard Winking smile

Hooking up the projects

You can now add the reference to the .Net Standard in your Android and iOS project. If you created a new namespace I strongly recommend you refactor them after adding them to your projects. Or else your refactoring tool of choice will only do half the magic and you will still have some work left to do.

If you are using a UWP project please read the section bellow as you will need to make some additional steps to make it work.

Fixing the csproj for Xamarin Forms

Unfortunately when moving a Xamarin Forms app over to .Net Standard you will get weird compilation errors. The cause of this is that the XAML files are referenced in the csproj file:

02_1_RemoveEmbeddedResources

Simply remove them as they are not needed and the compile errors should be history.

When using UWP

If you are using UWP as a target (I.e. using the default Project provided up to VS 2015.4). You will have to remove and add the project anew:

If you are unsure if you really have to update your UWP project. Check if you have a project.json file in your UWP project. If the answer is yes, I’m afraid you will have to follow the following steps.

  1. Remove the UWP project from the solution in Visual Studio
  2. Rename the UWP project folder in the file explorer
  3. Add a new UWP project in Visual Studio (with the same name as the one just removed)
  4. Set the minimal supported Windows 10 version to the Fall creators update

    VS Dialog Window with Target and Minimum Version set to Fall Creators Update
  5. Add any NuGet references the just removed project had (you can peek into the project.json file in the renamed location if you are unsure which packages to add)
  6. Copy and paste all your UWP files (except the project.json)
  7. Add a reference to the Standard Library project

If you know an easier way to upgrade a UWP project, please let me know in the comments bellow Smile

Conclusion

In this post we went over the steps required to migrate an existing PCL project to .Net Standard. All the steps were done with Visual Studio 15.4.

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PureLayout is a library for iOS developers that allows to create UI views in code behind with ease. With PureLayout.Net this option is now available for Xamarin.iOS.

Since PureLayout.Net is based on the idea of defining your UI in code you might be tempted, especially as a C# developer, to dismiss it as an utterly bad idea. Because defining UIs in code is such a no-no right? Well actually no, not under iOS. The standard approach under iOS is to use the Storyboard to define your UIs and your screen flow. This is great at first since it is very much like Windows Forms with all it’s drag and drop goodness. The problem arises in two areas:

  1. Having more then one person editing the Storyboard
  2. Sharing standard values such as Margins over the entire UI

TL;DR;Define your UIs in a reusable way that allows to share design standards and reduce duplication within UI work. Enable collaboration on UIs without the fear of merge conflicts by using PureLayout.Net. Which you will be able to use in no-time.

Since the storyboard is one large (generated) XML file. Any change to the UI is stored in a single location. In a larger project this will mean that whenever two or more people will want to make changes to the UI a merge conflict could arise. Should a merge conflict arise… Well to put it short you are out of luck. Since the XML gets generated it is not human friendly to merge. An error while merging will result in the entire UI of the app being in tatters. Now one could mitigate this problem to a certain degree by using XIBs. But those come with some extra glue code to get it running. Plus there is still this second point.

If you are working on a larger app, you will (want to) have some sort of a style guide. In it you will define a set of defined constants for your colours, margins, text sizes, fonts etc.. Going with the Storyboard or XIB designer will not provide you with a central coded style file. The only way to define and distribute the style is in a written text document such as a Word-, PDF-File or a Wiki page. This approach comes down to every one, who works on the UI, needing to know this document. The current version may I add and apply the styles. This can be a challenge to say the least.

All this can easily be avoided by using PureLayout.Net. - Which I hope does not come as surprise at this moment Winking smile

Where to get it

Simply add the NuGet package to your iOS project and you will be all set:

Install-Package PureLayout.Net

How to get started

A getting started guide can be found on the projects GitHub page.

Thank you

I would like to point out that PureLayout.Net is only a wrapper around the existing PureLayout library written Objective-C. Therefore a big thank you to Tyler Fox the creator and Mickey Reiss for currently maintaining the library.

Further I would like to thank Samuel Debruyn for helping me a lot on the topics of wrappers with his blog post.