SoundService.cs

/// <summary>
/// Sound Service
/// </summary>
public interface ISoundService
{
    /// <summary>
    /// Play Embedded Sound from Resources
    /// Usage example: ISoundService.PlaySound("success.mp3");
    /// </summary>
    /// <param name="sound">sound resource name with extension</param>
    void PlaySound(string sound);
}

public  partial class SoundService : ISoundService
{
    public void PlaySound(string sound)
    {
        #if ANDROID
        PlayAndroidSound(sound);
        #elif IOS
        PlayIosSound(sound);
        #endif
    }
}