Android RuntimePermissionsExtended

RuntimePermissionsExtended
Nebojša Vukšić

Nebojša Vukšić
Android developer @ codecentric
Founder of Kotlin User Group Serbia
TheTechW0lf
nebojsa92vuksic@gmail.com

Kotlin User Group Serbia
https://www.meetup.com/Serbia-Kotlin-User-Group
https://www.facebook.com/kotlinserbia/
https://twitter.com/kotlin_serbia

Android permissions definition
● part of Android security system
● used to control access to system features, data, etc.
● apps are in sandbox
● needed permission needs to be annotated in
AndroidManifest.xml
<uses-permission android:name="android.permission.CAMERA" />

Pre-Marshmallow
● targetSdkVersion < 23
● all permissions are granted in
install time
● less control for user
● no explanation for permission
usage
● when app is updated we need to
check additional permissions

After Marshmallow
● targetSdkVersion >= 23
● permissions are requested in
runtime
● all edge cases need to be
covered
● User can revoke permission from
settings screen
● Process is revoked

Permission protection level
● Normal permissions
● Dangerous permissions
● Signature permissions
● Signature and system permissions

Normal permissions
● granted when app is installed
● they are not risk for users data privacy and can’t affect other apps
Permission list:
● ACCESS_NETWORK_STATE
● BLUETOOTH
● INTERNET
● NFC
● VIBRATE
● WAKE_LOCK
● etc...

Dangerous permissions
● requested in runtime
● when permission from one group
is granted, all permissions in
group are granted
● they are risk for data privacy and
can affect other apps

Pre-Marshmallow - targetSdk < 23
import kotlinx.android.synthetic.main.activity_camera.*
class CameraActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_camera)
setSupportActionBar(toolbar)
//Start camera preview
startCameraPreviewScreen()
}
}

After Marshmallow - targetSdk >= 23
if (PermissionChecker.checkSelfPermission(this, android.Manifest.permission.CAMERA)
== PackageManager.PERMISSION_GRANTED) {
}
}
}

private val REQUEST_CAMERA_PERMISSION: Int = 1
} else {
ActivityCompat.requestPermissions(this, arrayOf<String>(android.Manifest.permission.CAMERA), REQUEST_CAMERA_PERMISSION)
}
}
}

override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
when (requestCode) {
REQUEST_CAMERA_PERMISSION -> {
if (grantResults.filterNot { it == PackageManager.PERMISSION_GRANTED }.isEmpty()) {
} else {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, android.Manifest.permission.CAMERA)) {
showSnackBarWithExplanation()
} else {
startGoToSettingsScreenIntent()
}
}
}
}
}

} else {
} else {
ActivityCompat.requestPermissions(this, arrayOf(android.Manifest.permission.CAMERA), REQUEST_CAMERA_PERMISSION)
}
}
}
}

It’s time to become extended!

RuntimePermissionExtended
} else {
} else {
}
}
}
}
OnPermissionGranted Block
OnExplanationNeeded Block
OnPermissionDenied Block

inline fun handlePermission(onGranted: () -> Unit, onExplanationNeeded: () -> Unit, onDenied: () -> Unit) {
onGranted()
} else {
onExplanationNeeded()
} else {
onDenied()
}
}
}
inline modifier - inlines onGranted, onDenied an onExplanationNeeded functions on call site

handlePermission(
onGranted = {
},
onExplanationNeeded = {
//Show explanation
},
onDenied = {
}
)
}
}

inline fun handlePermission(permission: AppPermission, onGranted: () -> Unit, onExplanationNeeded: () -> Unit, onDenied: () -> Unit) {
if (PermissionChecker.checkSelfPermission(this, permission.permissionName)
onGranted()
} else {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, permission.permissionName)) {
onExplanationNeeded()
} else {
onDenied()
}
}
}
sealed class AppPermission(val permissionName: String, val requestCode: Int, val deniedMessageId: Int, val explanationMessageId: Int) {
companion object { val permissions: List<AppPermission> by lazy { listOf(CAMERA) } }
object CAMERA: AppPermission(permissionName = Manifest.permission.CAMERA,
requestCode = 1,
deniedMessageId = R.string.permission_camera_denied,
explanationMessageId = R.string.permission_camera_explanation)
}

handlePermission(AppPermission.CAMERA,
onGranted = {
},
//Show explanation
},
onDenied = {
}
)
}
}
No information about requested permission

inline fun handlePermission(permission: AppPermission, onGranted: () -> Unit, onExplanationNeeded: (AppPermission) -> Unit,
onDenied: (AppPermission) -> Unit) {
onGranted()
} else {
onExplanationNeeded(permission)
} else {
onDenied(permission)
}
}
}
sealed class AppPermission(val permissionName: String, val requestCode: Int, val deniedMessageId: Int, val explanationMessageId: Int) {
companion object { val permissions: List<AppPermission> by lazy { listOf(CAMERA) } }
object CAMERA: AppPermission(permissionName = Manifest.permission.CAMERA,
requestCode = 1,
deniedMessageId = R.string.permission_camera_denied,
explanationMessageId = R.string.permission_camera_explanation)
}

onGranted = {
},
onExplanationNeeded = { permission ->
showSnackBarWithExplanation(permission.explanationMessageId)
},
onDenied = { permission ->
ActivityCompat.requestPermissions(this, arrayOf(permission.permissionName), permission.requestCode)
}
)
}
}

onGranted = {
},
showSnackBarWithExplanation(it.explanationMessageId)
},
onDenied = {
ActivityCompat.requestPermissions(this, arrayOf(it.permissionName), it.requestCode)
}
)
}
}

inline fun handlePermission(permission: AppPermission, onGranted: () -> Unit, onExplanationNeeded: (AppPermission) -> Unit,
onGranted()
} else {
} else {
}
}
}

inline fun Activity.handlePermission(permission: AppPermission, onGranted: () -> Unit, onExplanationNeeded: (AppPermission) -> Unit,
onGranted()
} else {
} else {
}
}
}
fun Activity.isPermissionGranted(permission: AppPermission)
= (PermissionChecker.checkSelfPermission(this, android.Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED)
fun Activity.isExplanationNeeded(permission: AppPermission)
= ActivityCompat.shouldShowRequestPermissionRationale(this, permission.permissionName)

if (isPermissionGranted(this, permission.permissionName)
onGranted()
} else {
if (isExplanationNeeded(this, permission.permissionName)) {
} else {
}
}
}

when {
isPermissionGranted(permission) -> onGranted()
isExplanationNeeded(permission) -> onExplanationNeeded(permission)
else -> onDenied(permission)
}
}

onGranted = {
},
},
onDenied = {
ActivityCompat.requestPermissions(this, arrayOf(it.permissionName), it.requestCode)
}
)
}
}
fun Activity.requestPermission(permission: AppPermission)
= ActivityCompat.requestPermissions(this, arrayOf(permission.permissionName), permission.requestCode)

onGranted = {
},
},
onDenied = {
requestPermission(it)
}
)
}
}
fun Activity.requestPermission(permission: AppPermission)
= ActivityCompat.requestPermissions(this, arrayOf(permission.permissionName), permission.requestCode)

Don’t forget about onRequestPermissionResult

} else {
} else {
startGoToSettingsIntent()
}
}
}
}
}

fun Activity.onPermissionRequestResultReceived(requestCode: Int, grantResults: IntArray,
onGranted: () -> Unit,
onExplanationNeeded: (AppPermission) -> Unit,
AppPermission.permissions.find { requestCode == it.requestCode }?.let {
when {
arePermissionsGranted(grantResults) -> onGranted()
isExplanationNeeded(it) -> onExplanationNeeded(it)
else -> onDenied(it)
}
}
}
private fun arePermissionsGranted(grantResults: IntArray) = grantResults.filterNot {
it == PackageManager.PERMISSION_GRANTED
}.isEmpty()

onPermissionRequestResultReceived(requestCode, grantResults,
onGranted = {
},
},
onDenied = {
}
)
}

Overview - before and now
} else {
} else {
ActivityCompat.requestPermissions(this, arrayOf(android.Manifest.permission.CAMERA),
REQUEST_CAMERA_PERMISSION)
}
}
}
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults:
IntArray) {
showCameraPreviewScreen()
} else {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, android.Manifest.permission.CAMERA)){
} else {
}
}
}
}
}
}
onGranted = {
},
showSnackbarExplanation
},
onDenied = {
requestPermission(it)
}
)
}
override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults:
IntArray) {
onPermissionRequestResultReceived(requestCode, grantResults,
onGranted = {
},
showSnackbarExplanation()
},
onDenied = {
}
)
}
}
Before Now

Summary
● use PermissionChecker
● extension functions
● higher order functions
● use combination of two concepts to reduce amount of
boilerplate code
● use inline modifier

Resources
● RuntimePermissionsExtended
● Official Kotlin documentation
● Official Kotlin Github
● Kotlin koans
● Awesome Kotlin – collection of materials
● Slack kanal
● #droidconpl2015 - Shintaro Katafuchi 'Managing Runtime Permissions'
● Sonja Kesić from Endava: May I? - droidcon Zagreb 2016
● Runtime Permissions - official Android documentation
● PermissionsDispatcher library

Android Serbia
Slack team of local Android community
Join us:
https://android-serbia.slack.com/

Nebojša Vukšić
Android developer @ codecentric
Founder of Kotlin User Group Serbia
nebojsa92vuksic@gmail.com
Kotlin User Group Serbia
https://www.meetup.com/Serbia-Kotlin-User-Group
https://www.facebook.com/kotlinserbia/
https://twitter.com/kotlin_serbia
TheTechW0lf

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