Xamarin Forms Hide a Button on iOS and Show it on Android

// IOS, Android, WP
SomeButton.IsVisible = Device.OnPlatform<bool>(false, true, true);

Or

if (Device.OS == TargetPlatform.Android)
{
    SomeButton.IsVisible = true;
}
else
...

If you want to do it on XAML, in order to hide a view on a specific platform, you can use this:

  <Button>
      <Button.IsVisible>
        <OnPlatform x:TypeArguments="x:Boolean"
                      iOS="false"
                      Android="true"/>
      </Button.IsVisible>
    </Button>

Hope it helps!