Android M request permission non activity

I found a workaround which seems to work fine. The trick is to create a transparent activity which is only there to request the permissions and is finished immediately afterwards. You’ll still need a context of course but it doesn’t have to be an activity.
The activity can return the result (granted or denied) via a broadcast (since startActivtyForResult is not possible outside of an activity).

You can use this activity:

import android.content.Intent
import android.content.pm.PackageManager
import android.os.Bundle
import android.support.v4.app.ActivityCompat
import android.support.v7.app.AppCompatActivity

internal const val PERMISSIONS_KEY = "permissions"
internal const val ACTION_PERMISSIONS_GRANTED = "GetPermissionsActivity.permissions_granted"
internal const val ACTION_PERMISSIONS_DENIED = "GetPermissionsActivity.permissions_denied"

class GetPermissionsActivity: AppCompatActivity() {

    private val permissionRequestCode = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        ActivityCompat.requestPermissions(
            this,
            intent.getStringArrayExtra(PERMISSIONS_KEY),
            permissionRequestCode
        )
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        if (requestCode == permissionRequestCode) {
            if ((grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                sendBroadcast(Intent(ACTION_PERMISSIONS_GRANTED))
            } else {
                sendBroadcast(Intent(ACTION_PERMISSIONS_DENIED))
            }
            finish()
        } else {
            super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        }
    }
}

And this style for the activity

<style name="Theme.Transparent" parent="Theme.AppCompat">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">false</item>
    <item name="android:windowAnimationStyle">@null</item>
</style>

In the manifest:

<activity android:name="GetPermissionsActivity" android:theme="@style/Theme.Transparent" />

And then use it like this (context required)

class SomeClass : BroadcastReceiver() {

    private fun someFunction(context: Context) {
        val intentFilter = IntentFilter()
        intentFilter.addAction(ACTION_PERMISSIONS_GRANTED)
        intentFilter.addAction(ACTION_PERMISSIONS_DENIED)
        context.registerReceiver(this, intentFilter)
        val intent = Intent(context, GetPermissionsActivity::class.java)
        intent.putExtra(PERMISSIONS_KEY, arrayOf(<your permissions>))
        context.startActivity(intent)
    }

    override fun onReceive(context: Context, intent: Intent) {
        when {
            intent.action == ACTION_PERMISSIONS_GRANTED -> {
                context.unregisterReceiver(this)
                onPermissionsGranted()
            }
            intent.action == ACTION_PERMISSIONS_DENIED -> {
                context.unregisterReceiver(this)
                onPermissionsDenied()
            }
            else -> super.onReceive(context, intent)
        }
    }

    private fun onPermissionsGranted() {
        // ...
    }

    private fun onPermissionsDenied() {
        // ...
    }
}