Xamarin.Forms DependencyService Android implementation
Example
The Android specific implementation is a bit more complex because it forces you to inherit from a native Java.Lang.Object and forces you to implement the IOnInitListener interface. Android requires you to provide a valid Android context for a lot of the SDK methods it exposes. Xamarin.Forms exposes a Forms.Context object that provides you with a Android context that you can use in such cases.
using Android.Speech.Tts;
using Xamarin.Forms;
using System.Collections.Generic;
using DependencyServiceSample.Droid;
public class TextToSpeechAndroid : Java.Lang.Object, ITextToSpeech, TextToSpeech.IOnInitListener
{
TextToSpeech _speaker;
public TextToSpeechAndroid () {}
public void Speak (string whatToSay)
{
var ctx = Forms.Context;
if (_speaker == null)
{
_speaker = new TextToSpeech (ctx, this);
}
else
{
var p = new Dictionary<string,string> ();
_speaker.Speak (whatToSay, QueueMode.Flush, p);
}
}
#region IOnInitListener implementation
public void OnInit (OperationResult status)
{
if (status.Equals (OperationResult.Success))
{
var p = new Dictionary<string,string> ();
_speaker.Speak (toSpeak, QueueMode.Flush, p);
}
}
#endregion
}
When you've created your class you need to enable the DependencyService to discover it at run time. This is done by adding an [assembly] attribute above the class definition and outside of any namespace definitions.
using Android.Speech.Tts;
using Xamarin.Forms;
using System.Collections.Generic;
using DependencyServiceSample.Droid;
[assembly: Xamarin.Forms.Dependency (typeof (TextToSpeechAndroid))]
namespace DependencyServiceSample.Droid {
...
This attribute registers the class with the DependencyService so it can be used when an instance of the ITextToSpeech interface is needed.
