<SearchBar x:Name="searchBar"
               Placeholder="Search"
               TextChanged="OnSearchTextChanged"
               TextColor="{DynamicResource NoteTextDark}">
            <SearchBar.BackgroundColor>
                <OnPlatform x:TypeArguments="Color">
                        <On Platform="Android" Value="{DynamicResource NotesEditorColor}" />
                </OnPlatform>      
            </SearchBar.BackgroundColor>

if (DeviceInfo.Platform == DevicePlatform.Android) 
                {
                    searchBar.SetDynamicResource(SearchBar.BackgroundColorProperty, "NotesEditorColor");
                }