Android 6.0 Runtime Permissions

(a code lab)

Code Lab Objective

Experiment with Android 6.0 Runtime Permissions

You do the experimenting!
Or, let the presenter do the experimenting, while you sit back and relax, as why should you do all the work?

Runtime Permissions

Legacy Apps

(targetSdkVersion < 23)

No code changes
Behavior akin to "app ops"
- User can revoke dangerous permissions at runtime
- Affected APIs return bogus results

Runtime Permissions

Modern Apps

(targetSdkVersion >= 23)

Same uses-permission elements
Must request dangerous permissions
- Modal dialog-style UI
- User can accept, deny, or deny with extreme prejudice

Runtime Permission Mechanics

checkSelfPermission()

Context and ContextCompat
Given name of permission, tells you if you have it

Runtime Permission Mechanics

requestPermissions()

Activity and ActivityCompat
Given array of permission names, prompts user to accept/deny them

One "pane" to dialog per permission group
Get result in onRequestPermissionsResult()

Runtime Permission Mechanics

shouldShowRequestPermissionRationale()

Activity and ActivityCompat
Given permission name, returns true if...

...you have never asked for this permission, or...
...you asked, the user denied it, but the user has not blocked further requests

Use: educate user about upcoming permission request

Possible Runtime Permission States

We have never asked for the permission
We asked for the permission, and it was granted
We asked for the permission, and it was denied
We asked for the permission, and it was denied, and the user took out a restraining order against us

Code Lab Time!

Code Lab Resources

Starter project
PDF with instructions
Finished project ...if you just want to see the results

Task #0: Install the Android 6.0 SDK

If you have done this already, great!

If you have not done this already... just sit back and watch!

Task #1: Import the Starter Project

RuntimePermTutorial.zip file
Unzip in some likely spot
File > New... > Import Project from Android Studio

Reviewing the Sample App

Landscape and portrait layouts, two big buttons
- Take a picture
- Record a video
Dependencies
- Icon button library
- CWAC-Cam2 for camera stuff

Task #2: Upgrade Gradle for Android 6.0

compileSdkVersion 23
buildToolsVersion "23.0.0"
targetSdkVersion 23

So, What Are We Gonna Do About Permissions?

Ask for CAMERA and WRITE_EXTERNAL_STORAGE on first run, as the app is totally useless without them
Ask for RECORD_AUDIO when they click the "Record Video" button, as we will not need it before then
Ask for whatever permissions we do not hold when they click a button that needs them
If they deny permissions, then click a button, explain why we are going to ask for the permissions again

Task #3: Add Fields for First-Run Detection

private static final String PREF_IS_FIRST_RUN="firstRun";
private SharedPreferences prefs;

Task #4: Initialize the Preferences

Add the following to onCreate():

prefs=PreferenceManager.getDefaultSharedPreferences(this);

Task #5: Use the Preferences to Track the First Run

private boolean isFirstRun() {
  boolean result=prefs.getBoolean(PREF_IS_FIRST_RUN, true);
  
  if (result) {
    prefs.edit().putBoolean(PREF_IS_FIRST_RUN, false).apply();
  }
  
  return(result);
}

Task #6: Check for First Run

Add the following to the bottom of onCreate():

if (isFirstRun()) {
  // TODO
}

Task #7: Add Some Static Imports

import static android.Manifest.permission.CAMERA;
import static android.Manifest.permission.RECORD_AUDIO;
import static android.Manifest.permission.WRITE_EXTERNAL_STORAGE;

Task #8: List our Take-Picture Permissions

private static final String[] PERMS_TAKE_PICTURE={
  CAMERA,
  WRITE_EXTERNAL_STORAGE
};

Task #9: Add Our Take-Picture Permission Result Code

private static final int RESULT_PERMS_INITIAL=1339;

Task #10: Add the Support Library for Permission Compatibility Code

dependencies {
  compile 'com.commonsware.cwac:cam2:0.2.+'
  compile 'com.githang:com-phillipcalvin-iconbutton:1.0.1@aar'
  compile 'com.android.support:support-v4:23.0.1'
}

Task #11: Ask for Permission

if (isFirstRun()) {
  ActivityCompat.requestPermissions(this, PERMS_TAKE_PICTURE,
    RESULT_PERMS_INITIAL);
}

Task #12: Add Permission Callback Stub

@Override
public void onRequestPermissionsResult(int requestCode,
  String[] permissions, int[] grantResults) {
    // TODO
}

Task #13: Try It Out!

Run the app ...and it should prompt you for permissions
Press BACK
Run the app again ...and it should not prompt you for permissions
Uninstall the app ...so we start from scratch with permissions on the next run

Task #14: Create a Permission-Check Helper Method

private boolean hasPermission(String perm) {
  return(ContextCompat.checkSelfPermission(this, perm)==
    PackageManager.PERMISSION_GRANTED);
}

Task #15: See If We Can Take a Picture

private boolean canTakePicture() {
  return(hasPermission(CAMERA) &&
    hasPermission(WRITE_EXTERNAL_STORAGE));
}

Task #16: No, I Mean See If We Can Take a Picture

public void takePicture(View v) {
  if (canTakePicture()) {
    takePictureForRealz();
  }
}

Task #17: See If We Should Show Some Rationale

private boolean shouldShowTakePictureRationale() {
  return(ActivityCompat.shouldShowRequestPermissionRationale(this,
            CAMERA) ||
         ActivityCompat.shouldShowRequestPermissionRationale(this,
            WRITE_EXTERNAL_STORAGE));
}

Task #18: Use That New Method, As It Is Lonely

public void takePicture(View v) {
  if (canTakePicture()) {
    takePictureForRealz();
  }
  else if (shouldShowTakePictureRationale()) {
    // TODO
  }
}

Task #19: Add a TextView As Our "Breadcrust"

@+id/breadcrust
visibility set to gone
Add to both layout and layout-land

Task #20: Find Our Breadcrust

private TextView breadcrust; as field
breadcrust=(TextView)findViewById(R.id.breadcrust); in onCreate()

Task #21: Define a Picture Rationale Message

You need to grant us
permission! Tap the Take Picture button again, and we will ask
for permission.

Task #22: Define Another Result Code

private static final int RESULT_PERMS_TAKE_PICTURE=1340;

Task #23: Net the Permissions

requestPermissions() prompts user for everything we ask for ...even if they granted the permission to us before
This is an icky method, too big for this slide

Task #24: Show Rationale When Needed

"What is it that you want?"

"I want the code!"

"You can't handle the code!"

(...or at least this slide can't)

Task #25: Deal with the Results

If we requested permissions, and we can take a picture, go ahead
If we requested permissions, cannot take a picture, but should show rationale, do that
Otherwise, we're stuck
(and, yes, the code is too long for the slide here too)

Task #26: Try It Out!

Run the app, reject one of the permissions
Tap the picture button, get rationale
Tap the picture button again, reject the permission again
Uninstall the app

Task #27: Once More, From the Top, with Video

private boolean canRecordVideo() {
  return(canTakePicture() && hasPermission(RECORD_AUDIO));
}

Task #28: Only Record If We Can

public void recordVideo(View v) {
  if (canRecordVideo()) {
    recordVideoForRealz();
  }
}

Task #29: U Can Needz Video Rationale?

private boolean shouldShowRecordVideoRationale() {
  return(shouldShowTakePictureRationale() ||
    ActivityCompat.shouldShowRequestPermissionRationale(this,
      RECORD_AUDIO));
}

Task #30: Ask All the Permissions! And, Um, Results Too!

private static final String[] PERMS_ALL={
  CAMERA,
  WRITE_EXTERNAL_STORAGE,
  RECORD_AUDIO
};
private static final int RESULT_PERMS_RECORD_VIDEO=1341;

Task #31: Really Record the Video. Really.

(pretend that there is some code here)

Task #32: Handle the Results

(did I mention that runtime permissions are tedious?)

Task #33: Configuration Changes. Ugh.

private static final String STATE_BREADCRUST=
  "com.commonsware.android.perm.tutorial.breadcrust";

@Override
protected void onSaveInstanceState(Bundle outState) {
  super.onSaveInstanceState(outState);

  if (breadcrust.getVisibility()==View.VISIBLE) {
    outState.putCharSequence(STATE_BREADCRUST,
      breadcrust.getText());
  }
}

Task #33½: Configuration Changes. Ugh.

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
  super.onRestoreInstanceState(savedInstanceState);

  CharSequence cs=savedInstanceState.getCharSequence(STATE_BREADCRUST);
  
  if (cs!=null) {
    breadcrust.setVisibility(View.VISIBLE);
    breadcrust.setText(cs);
  }
}