Push notifications instant message receiving like on Whatsapp or Viber

Question

When Whatsapp (or Viber) iOS application is completely turned off (removed from the background) message receiving is handled via push notifications as expected.
When you wake up Whatsapp (or Viber) from push notification, it instantly shows all received messages without explicitly taking any time to download them from the server.
Actually, it looks like every push notification wakes up the app for enough time to download message that had been sent, which is, I belive, impossible in iOS.

Does anyone have an idea how did they implemented that fast receiving of bunch of messages?

Answer 1

Your app gets invoke in background, no matter it is in background mode or kill mode. your app will be active upto your local notification sould plays ( Max 30 seconds ).

Use below structure to achieve your task.

Use this simplepush.php file

<?php

// Put your device token here (without spaces):

    
      $deviceToken = '1234567890123456789';
//

    
// Put your private key's passphrase here:
$passphrase = 'ProjectName';

// Put your alert message here:
$message = 'My first push notification!';



$ctx = stream_context_create();
stream_context_set_option($ctx, 'ssl', 'local_cert', 'PemFileName.pem');
stream_context_set_option($ctx, 'ssl', 'passphrase', $passphrase);

// Open a connection to the APNS server
$fp = stream_socket_client(
//  'ssl://gateway.push.apple.com:2195', $err,
    'ssl://gateway.sandbox.push.apple.com:2195', $err,
    $errstr, 60, STREAM_CLIENT_CONNECT|STREAM_CLIENT_PERSISTENT, $ctx);

if (!$fp)
    exit("Failed to connect: $err $errstr" . PHP_EOL);

echo 'Connected to APNS' . PHP_EOL;

// Create the payload body

$body['aps'] = array(
                     'content-available'=> 1,
                     'alert' => $message,
                     'sound' => 'default',
                     'badge' => 0,
                     );

    

// Encode the payload as JSON
    
$payload = json_encode($body);

// Build the binary notification
$msg = chr(0) . pack('n', 32) . pack('H*', $deviceToken) . pack('n', strlen($payload)) . $payload;

// Send it to the server
$result = fwrite($fp, $msg, strlen($msg));

if (!$result)
    echo 'Message not delivered' . PHP_EOL;
else
    echo 'Message successfully delivered' . PHP_EOL;

// Close the connection to the server
fclose($fp);

Use below commands to create pem file and use it in above code

$ openssl x509 -in aps_development.cer -inform der -out PushCert.pem

# Convert .p12 to .pem. Enter your pass pharse which is the same pwd that you have given while creating the .p12 certificate. PEM pass phrase also same as .p12 cert.  
$ openssl pkcs12 -nocerts -out PushKey1.pem -in pushkey.p12

Enter Import Password:

MAC verified OK

Enter PEM pass phrase:

Verifying - Enter PEM pass phrase:

# To remove passpharse for the key to access globally. This only solved my stream_socket_client() & certificate capath warnings.
$ openssl rsa -in PushKey1.pem -out PushKey1_Rmv.pem

Enter pass phrase for PushChatKey1.pem:

writing RSA key

# To join the two .pem file into one file:
$ cat PushCert.pem PushKey1_Rmv.pem > ApnsDev.pem

After that go to simplepush.php location and fire command -> php simplepush.php

This way you can test your push kit notification setup architecture.

https://www.raywenderlich.com/123862/push-notifications-tutorial

Download

import UIKit
import PushKit


class AppDelegate: UIResponder, UIApplicationDelegate,PKPushRegistryDelegate{



func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {


    let types: UIRemoteNotificationType = [.Alert, .Badge, .Sound]
    application.registerForRemoteNotificationTypes(types)

    self. PushKitRegistration()

    return true
}



//MARK: - PushKitRegistration

func PushKitRegistration()
{

    let mainQueue = dispatch_get_main_queue()
    // Create a push registry object
    if #available(iOS 8.0, *) {

        let voipRegistry: PKPushRegistry = PKPushRegistry(queue: mainQueue)

        // Set the registry's delegate to self

        voipRegistry.delegate = self

        // Set the push type to VoIP

        voipRegistry.desiredPushTypes = [PKPushTypeVoIP]

    } else {
        // Fallback on earlier versions
    }


}


@available(iOS 8.0, *)
func pushRegistry(registry: PKPushRegistry!, didUpdatePushCredentials credentials: PKPushCredentials!, forType type: String!) {
    // Register VoIP push token (a property of PKPushCredentials) with server

    let hexString : String = UnsafeBufferPointer<UInt8>(start: UnsafePointer(credentials.token.bytes),
        count: credentials.token.length).map { String(format: "%02x", $0) }.joinWithSeparator("")

    print(hexString)


}


@available(iOS 8.0, *)
func pushRegistry(registry: PKPushRegistry!, didReceiveIncomingPushWithPayload payload: PKPushPayload!, forType type: String!) {
    // Process the received push
    // From here you have to schedule your local notification

}

}

Answer 2

You should probably use PushKit, along with the Voice over IP background mode enabled in your Xcode Project > Capabilities pane. That way VoIP push notification can wake up your application, so you can process the received data and display it. Also VoIP pushes have several advantages over standard push notifications. More info can be found here.