Platform specific

No let's say that we are writing a Xamarin forms app and for some bizarre reason we want our application to have a different background color in our different OS's, let's say for the sake of argument that we wanted:

• Android background to be Black
• IOS background to be White
• UWP background to be DarkGrey

well we could set those values directly in our xaml

<?xml version="1.0" encoding="utf-8" ?>

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"

             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"

             xmlns:local="clr-namespace:pav01.OsSpecific"

             x:Class="pav01.OsSpecific.MainPage">

    <ContentPage.BackgroundColor>

        <OnPlatform x:TypeArguments="Color">

            <On Platform="Android">Black</On>

            <On Platform="IOS">White</On>

            <On Platform="UWP">DarkGray</On>

        </OnPlatform>

    </ContentPage.BackgroundColor>

   

    <StackLayout>

        <Label Text="Welcome to Xamarin.Forms!" 

               HorizontalOptions="Center"

               VerticalOptions="CenterAndExpand" />     

    </StackLayout>

</ContentPage>

and that's it, our apps background color is now different based on the Platform we are deploying our app to.

there's also a non declarative way to execute platform specific logic using pre-processor directives

public static string GetPlatformName() { string result = "notset"; #if __ANDROID__ result = "Droid"; #elif __IOS__ result = "IOS"; #elif WINDOWS_UWP result = "UWP"; #endif return result; }

these can be leveraged inside of Shared projects to compile separate code for different

Symbol	What it represents
#if __MOBILE__	Any mobile project (vs. desktop)
#if __ANDROID__	Xamarin.Android - defined by the compiler
#if __IOS__	Xamarin.iOS - defined by the compiler
#if __MAC__	Xamarin.Mac - defined by the compiler
#if __TVOS__	iOS tvOS - defined by the compiler
#if __WATCHOS__	iOS watchOS - defined by the compiler
#if WINDOWS_UWP	Windows 10 UWP - defined in build settings

platforms