Xamarin.Forms Book - BlackCat F#

Xamarin.Forms docs / eBook / Related samples

Simple Xamarin.Forms application for Android and iOS, written in F#. The app demonstrates loading text from a file, and displaying it on the screen:

iOS app showing text loaded from file

// Get access to the text resource.
let assembly = base.GetType().GetTypeInfo().Assembly
let resource = "TheBlackCat.txt"

// Get all the lines of the file.
let lines = seq { use stream = assembly.GetManifestResourceStream(resource)
                    use reader = new StreamReader(stream)
                    while not reader.EndOfStream do
                        yield reader.ReadLine() }


BlackCatPage.fs line 21 might need to be updated to:

let resource = "BlackCat.TheBlackCat.txt"

if you experience a null reference exception. This relates to the way the default name for the resource is generated. TheBlackCat.txt is likely to work on Windows and BlackCat.TheBlackCat.txt on Visual Studio for Mac.


  • Visual Studio on Mac or Windows.
    • Mobile Development with .NET (Xamarin) workload installed.
    • F#
  • To test and deploy to iOS devices:
    • Mac computer with the latest version of macOS.
    • Latest version of Xcode from Apple on the Mac.
    • If you're using Windows, the Mac should be available on the network.

Running the sample

  1. Open the solution file (.sln) in Visual Studio.
  2. Use the Run button or menu to start the app.