Implementing Android 6.0 permissions in unity3d

Question

I've installed Android Support Library but in the developer.android site says that for implementing it on my project I need to edit my build.gradle file that I don't have because it's an Unity project.

I've created a build.gradle file copying the content of this website: http://gradleplease.appspot.com/ and I put that file on the root of my Unity project but when I try to use the library it does not work

if (ContextCompat.checkSelfPermission(thisActivity,
                                      Manifest.permission.READ_CONTACTS)
    != PackageManager.PERMISSION_GRANTED) {

    // Should we show an explanation?
    if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
                                                            Manifest.permission.READ_CONTACTS)) {

        // Show an expanation to the user *asynchronously* -- don't block
        // this thread waiting for the user's response! After the user
        // sees the explanation, try again to request the permission.

    } else {

        // No explanation needed, we can request the permission.

        ActivityCompat.requestPermissions(thisActivity,
                                          new String[]{Manifest.permission.READ_CONTACTS},
        MY_PERMISSIONS_REQUEST_READ_CONTACTS);

        // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
        // app-defined int constant. The callback method gets the
        // result of the request.
    }
}

Answer 1

You need Java code to ask for permission, and you need an interface into said Java code from Unity's C# runtime. You need to create a Unity Plugin to do this.

Below is the plugin that I've created to grant the WRITE_EXTERNAL_STORAGE permission at runtime.

You need a project structure like this:

Plugins/
  Android/
    NoodlePermissionGranter/
      project.properties
      AndroidManifest.xml
      NoodlePermissionGranter.cs
      libs/
        NoodlePermissionGranter.jar

NoodlePermissionGranter.cs:

      ///////////////////////////////////////////////////////////
     ///////////////// NoodlePermissionGranter /////////////////
    /// Implements runtime granting of Android permissions. ///
   /// This is necessary for Android M (6.0) and above. //////
  ///////////////////////////////////////////////////////////   
 //////////////////// Noodlecake Studios ///////////////////
///////////////////////////////////////////////////////////

using UnityEngine;
using System.Collections;
using System;

public class NoodlePermissionGranter : MonoBehaviour {

    // subscribe to this callback to see if your permission was granted.
    public static Action<bool> PermissionRequestCallback;

    // for now, it only implements the external storage permission
    public enum NoodleAndroidPermission
    {
        WRITE_EXTERNAL_STORAGE
    }
    public static void GrantPermission(NoodleAndroidPermission permission) 
    {
        if (!initialized)
            initialize ();

        noodlePermissionGranterClass.CallStatic ("grantPermission", activity, (int)permission);
    }







      //////////////////////////////
     /// Initialization Stuff /////
    //////////////////////////////

    // it's a singleton, but no one needs to know about it. hush hush. dont touch me.
    private static NoodlePermissionGranter instance;
    private static bool initialized = false;

    public void Awake()
    {
        // instance is also set in initialize.
        // having it here ensures this thing doesnt break
        // if you added this component to the scene manually
        instance = this;
        DontDestroyOnLoad (this.gameObject);
        // object name must match UnitySendMessage call in NoodlePermissionGranter.java
        if (name != NOODLE_PERMISSION_GRANTER)
            name = NOODLE_PERMISSION_GRANTER;
    }


    private static void initialize()
    {
        // runs once when you call GrantPermission

        // add object to scene
        if (instance == null) {
            GameObject go = new GameObject();
            // instance will also be set in awake, but having it here as well seems extra safe
            instance = go.AddComponent<NoodlePermissionGranter>();
            // object name must match UnitySendMessage call in NoodlePermissionGranter.java
            go.name = NOODLE_PERMISSION_GRANTER; 
        }

        // get the jni stuff. we need the activty class and the NoodlePermissionGranter class.
        noodlePermissionGranterClass = new AndroidJavaClass("com.noodlecake.unityplugins.NoodlePermissionGranter");
        AndroidJavaClass u3d = new AndroidJavaClass ("com.unity3d.player.UnityPlayer");
        activity = u3d.GetStatic<AndroidJavaObject> ("currentActivity");

        initialized = true;
    }







      ///////////////////
     //// JNI Stuff ////
    ///////////////////

    static AndroidJavaClass noodlePermissionGranterClass;
    static AndroidJavaObject activity;
    private const string WRITE_EXTERNAL_STORAGE="WRITE_EXTERNAL_STORAGE";
    private const string PERMISSION_GRANTED = "PERMISSION_GRANTED"; // must match NoodlePermissionGranter.java
    private const string PERMISSION_DENIED = "PERMISSION_DENIED"; // must match NoodlePermissionGranter.java
    private const string NOODLE_PERMISSION_GRANTER = "NoodlePermissionGranter"; // must match UnitySendMessage call in NoodlePermissionGranter.java

    private void permissionRequestCallbackInternal(string message)
    {
        // were calling this method from the java side.
        // the method name and gameobject must match NoodlePermissionGranter.java's UnitySendMessage
        bool permissionGranted = (message == PERMISSION_GRANTED);
        if (PermissionRequestCallback != null)
            PermissionRequestCallback (permissionGranted);
    }
}

NoodlePermissionGranter.java:

package com.noodlecake.unityplugins;


      ///////////////////////////////////////////////////////////
     ///////////////// NoodlePermissionGranter /////////////////
    /// Implements runtime granting of Android permissions. ///
   /// This is necessary for Android M (6.0) and above. //////
  ///////////////////////////////////////////////////////////   
 //////////////////// Noodlecake Studios ///////////////////
///////////////////////////////////////////////////////////

import android.Manifest;
import android.os.Build;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.util.Log;
import android.content.pm.PackageManager;
import java.io.File;
import com.unity3d.player.UnityPlayerActivity;
import com.unity3d.player.UnityPlayer;

public class NoodlePermissionGranter
{
    // Only implements WRITE_EXTERNAL_STORAGE so far.
    // Implement the rest by matching the enum in NoodlePermissionGranter.cs
    // to the getPermissionStringFromEnumInt below.

    private final static String UNITY_CALLBACK_GAMEOBJECT_NAME = "NoodlePermissionGranter";
    private final static String UNITY_CALLBACK_METHOD_NAME = "permissionRequestCallbackInternal";
    private final static String PERMISSION_GRANTED = "PERMISSION_GRANTED"; // this will be an arg to the above method
    private final static String PERMISSION_DENIED = "PERMISSION_DENIED";

    public static String getPermissionStringFromEnumInt(int permissionEnum) throws Exception
    {
        switch (permissionEnum)
        {
            case 0:
                return Manifest.permission.WRITE_EXTERNAL_STORAGE;
            // "and the rest is still unwritten" - Natasha Bedingfield
        }
        Log.e("NoodlePermissionGranter", "Error. Unknown permissionEnum " + permissionEnum);
        throw new Exception(String.format("Error. Unknown permissionEnum %d",permissionEnum));
    }

    public static void grantPermission(Activity currentActivity, int permissionEnum)
    {
        // permission enum must match ordering in NoodlePermissionGranter.cs
        final Activity act = currentActivity;
        Log.i("NoodlePermissionGranter","grantPermission " + permissionEnum) ;
        if (Build.VERSION.SDK_INT < 23) {
            Log.i("NoodlePermissionGranter","Build.VERSION.SDK_INT < 23 (" + Build.VERSION.SDK_INT+")");
            UnityPlayer.UnitySendMessage(UNITY_CALLBACK_GAMEOBJECT_NAME, UNITY_CALLBACK_METHOD_NAME, PERMISSION_GRANTED);
            return;
        }

        try
        {
            final int PERMISSIONS_REQUEST_CODE = permissionEnum;
            final String permissionFromEnumInt = getPermissionStringFromEnumInt(permissionEnum);
            if (currentActivity.checkCallingOrSelfPermission(permissionFromEnumInt) == PackageManager.PERMISSION_GRANTED) {
                Log.i("NoodlePermissionGranter", "already granted");
                UnityPlayer.UnitySendMessage(UNITY_CALLBACK_GAMEOBJECT_NAME, UNITY_CALLBACK_METHOD_NAME, PERMISSION_GRANTED);
                return;
            }

            final FragmentManager fragmentManager = currentActivity.getFragmentManager();
            final Fragment request = new Fragment() {

                @Override public void onStart()
                {
                    super.onStart();
                    Log.i("NoodlePermissionGranter","fragment start");
                    String[] permissionsToRequest = new String [] {permissionFromEnumInt};
                    Log.i("NoodlePermissionGranter","fragment start " + permissionsToRequest[0]);
                    requestPermissions(permissionsToRequest, PERMISSIONS_REQUEST_CODE);
                }

                @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults)
                {
                    Log.i("NoodlePermissionGranter", "onRequestPermissionsResult");
                    if (requestCode != PERMISSIONS_REQUEST_CODE)
                        return;

                    if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                        // permission was granted, yay! Do the
                        // contacts-related task you need to do.
                        Log.i("NoodlePermissionGranter", PERMISSION_GRANTED);
                        UnityPlayer.UnitySendMessage(UNITY_CALLBACK_GAMEOBJECT_NAME, UNITY_CALLBACK_METHOD_NAME, PERMISSION_GRANTED);
                    } else {

                        // permission denied, boo! Disable the
                        // functionality that depends on this permission.
                        Log.i("NoodlePermissionGranter",PERMISSION_DENIED);
                        UnityPlayer.UnitySendMessage(UNITY_CALLBACK_GAMEOBJECT_NAME, UNITY_CALLBACK_METHOD_NAME, PERMISSION_DENIED);
                    }


                    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                    fragmentTransaction.remove(this);
                    fragmentTransaction.commit();

                    // shouldBeOkayToStartTheApplicationNow();
                }
            };

            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.add(0, request);
            fragmentTransaction.commit();
        }
        catch(Exception error)
        {
            Log.w("[NoodlePermissionGranter]", String.format("Unable to request permission: %s", error.getMessage()));
            UnityPlayer.UnitySendMessage(UNITY_CALLBACK_GAMEOBJECT_NAME, UNITY_CALLBACK_METHOD_NAME, PERMISSION_DENIED);
        }
    }

}

BuildNoodlePermissionGranter.sh

export JAVA_HOME=/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
ClASSPATH=$UNITY_ROOT"/Unity.app/Contents/PlaybackEngines/AndroidPlayer/Variations/mono/Release/Classes/classes.jar"

javac NoodlePermissionGranter.java -bootclasspath $ANDROID_SDK_ROOT/platforms/android-23/android.jar -classpath $ClASSPATH -d .
javap -s com.noodlecake.unityplugins.NoodlePermissionGranter
jar cvfM NoodlePermissionGranter.jar com/
rm -rf com

You need project.properties and a dummy AndroidManifest.xml in order to have Unity package a jar outside of Plugins/Android/libs

project.properties

target=android-9
android.library=true

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.noodlecake.unityplugins.noodlepermissiongranter"
    android:versionCode="1"
    android:versionName="1.0" >
    <uses-sdk android:targetSdkVersion="23" />
</manifest>

It'd be nice if the PermissionRequestCallback supplied the requested permission enum as a parameter, but UnityPlayer.UnitySendMessage only supports a single string argument and I decided not to implemented the string serialization (using JSON to do this would be a good choice).

Answer 2

Another addition to Jason's excellent code for Unity 5.3.3 and up (I'm using 5.4), I added this to the manifest to block Unity from automatically asking at launch:

 <application>
     <meta-data android:name="unityplayer.SkipPermissionsDialog" android:value="true" />
 </application>