Rendering audio to a file is an important feature of an audio synthesizer, but if the user can't share the file, then it's not very useful. In my second pass on my synthesizers, I'm adding the ability to share rendered audio files using email or text message.

The code for sharing audio files is tricky. You have to tell Unity to generate some Java code that launches something called an Intent. So this code basically instantiates the Java classes for the Intent and the File, then starts the activity for the intent.

Figuring out the code is tough, but you also need to change a setting in your player settings. Specifically, I couldn't get this code to work without Write Access: External (SDCard) enabled in Player Settings. Even if I am writing to internal storage only, I need to tell Unity to request external write access. I'm assuming that the extra privileges are needed for sharing the file.

Here's the code.

public static void ShareAndroid(string path)
{
    // create the Android/Java Intent objects
    AndroidJavaClass intentClass = new AndroidJavaClass("android.content.Intent");
    AndroidJavaObject intentObject = new AndroidJavaObject("android.content.Intent");

    // set properties of the intent
    intentObject.Call("setAction", intentClass.GetStatic("ACTION_SEND"));
    intentObject.Call("setType", "*/*");

    //instantiate the class Uri
    AndroidJavaClass uriClass = new AndroidJavaClass("android.net.Uri");

    // log the attach path
    Debug.Log("Attempting to attach file://" + path);

    // check if the file exists
    AndroidJavaClass fileClass = new AndroidJavaClass("java.io.File");
    AndroidJavaObject fileObject = new AndroidJavaObject("java.io.File", path);// Set Image Path Here
    //instantiate the object Uri with the parse of the url's file
    AndroidJavaObject uriObject = uriClass.CallStatic("parse", "file://" + path);
    // call the exists method on the File object
    bool fileExist = fileObject.Call("exists");
    Debug.Log("File exists: " + fileExist);

    // attach the Uri instance to the intent
    intentObject.Call("putExtra", intentClass.GetStatic("EXTRA_STREAM"), uriObject);

    // instantiate the current activity    
    AndroidJavaClass unity = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
    AndroidJavaObject currentActivity = unity.GetStatic("currentActivity");

    // start the new intent - for this to work, you must have Write Access: External (SDCard) enabled in Player Settings!
    currentActivity.Call("startActivity", intentObject);
}