is there automatic re-try to get GCM token (ios swift)? - ios

Question

I use this code to get GCM token (APNS and then GCM tokens).
Does retry happens automatically when GCM doesn't return token?
If so - where can i see it in code? and how often does this happen?
//push
// [START register_for_remote_notifications]
func registerForRemoteNotifications(application: UIApplication, launchOptions:[NSObject: AnyObject]?) -> Bool {
// [START_EXCLUDE]
// Configure the Google context: parses the GoogleService-Info.plist, and initializes
// the services that have entries in the file
var configureError:NSError?
GGLContext.sharedInstance().configureWithError(&configureError)
assert(configureError == nil, "Error configuring Google services: \(configureError)")
pushManager.gcmSenderID = GGLContext.sharedInstance().configuration.gcmSenderID
// [END_EXCLUDE]
// Register for remote notifications
if #available(iOS 8.0, *) {
let settings: UIUserNotificationSettings =
UIUserNotificationSettings(forTypes: [.Alert, .Badge, .Sound], categories: nil)
application.registerUserNotificationSettings(settings)
application.registerForRemoteNotifications()
} else {
// Fallback
let types: UIRemoteNotificationType = [.Alert, .Badge, .Sound]
application.registerForRemoteNotificationTypes(types)
}
// [END register_for_remote_notifications]
// [START start_gcm_service]
let gcmConfig = GCMConfig.defaultConfig()
gcmConfig.receiverDelegate = pushManager
GCMService.sharedInstance().startWithConfig(gcmConfig)
// [END start_gcm_service]
return true
}
func application(application: UIApplication, didRegisterUserNotificationSettings notificationSettings: UIUserNotificationSettings)
{
UIApplication.sharedApplication().registerForRemoteNotifications()
}
func subscribeToTopic() {
// If the app has a registration token and is connected to GCM, proceed to subscribe to the
// topic
if(pushManager.registrationToken != nil && pushManager.connectedToGCM) {
GCMPubSub.sharedInstance().subscribeWithToken(pushManager.registrationToken, topic: pushManager.subscriptionTopic,
options: nil, handler: {(NSError error) -> Void in
if (error != nil) {
// Treat the "already subscribed" error more gently
if error.code == 3001 {
print("Already subscribed to \(self.pushManager.subscriptionTopic)")
} else {
print("Subscription failed: \(error.localizedDescription)");
}
} else {
self.pushManager.subscribedToTopic = true;
NSLog("Subscribed to \(self.pushManager.subscriptionTopic)");
}
})
}
}
// [START connect_gcm_service]
func connectGcmService( application: UIApplication) {
if (self.pushManager.connectedToGCM == true)
{
return
}
// Connect to the GCM server to receive non-APNS notifications
GCMService.sharedInstance().connectWithHandler({
(NSError error) -> Void in
if error != nil {
print("Could not connect to GCM: \(error.localizedDescription)")
} else {
self.pushManager.connectedToGCM = true
print("Connected to GCM")
// [START_EXCLUDE]
self.subscribeToTopic()
// [END_EXCLUDE]
}
})
}
// [END connect_gcm_service]
// [START disconnect_gcm_service]
func disconnectGcmService(application: UIApplication) {
GCMService.sharedInstance().disconnect()
// [START_EXCLUDE]
self.pushManager.connectedToGCM = false
// [END_EXCLUDE]
}
// [END disconnect_gcm_service]
func application( application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken
deviceToken: NSData ) {
let tokenChars = UnsafePointer<CChar>(deviceToken.bytes)
var tokenString = ""
for i in 0..<deviceToken.length {
tokenString += String(format: "%02.2hhx", arguments: [tokenChars[i]])
}
print("tokenString: \(tokenString)")
pushManager.receiveApnsToken( application, deviceToken: deviceToken)
}
func application( application: UIApplication, didFailToRegisterForRemoteNotificationsWithError
error: NSError ) {
pushManager.receiveApnsTokenError( application, error: error)
}
func application( application: UIApplication,
didReceiveRemoteNotification userInfo: [NSObject : AnyObject]) {
pushManager.ackMessageReception( application, userInfo: userInfo)
}
func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject], fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
pushManager.ackMessageReception( application, userInfo: userInfo)
}
and PushManager class:
public class PushManager: NSObject, GGLInstanceIDDelegate, GCMReceiverDelegate {
var connectedToGCM = false
var subscribedToTopic = false
var gcmSenderID: String?
var registrationToken: String?
var registrationOptions = [String: AnyObject]()
let registrationKey = "onRegistrationCompleted"
let messageKey = "onMessageReceived"
let subscriptionTopic = "/topics/global"
// // [START register_for_remote_notifications]
func registerForRemoteNotifications(application: UIApplication, launchOptions: [NSObject: AnyObject]?) -> Bool {
// [START_EXCLUDE]
// Configure the Google context: parses the GoogleService-Info.plist, and initializes
// the services that have entries in the file
var configureError:NSError?
GGLContext.sharedInstance().configureWithError(&configureError)
assert(configureError == nil, "Error configuring Google services: \(configureError)")
gcmSenderID = GGLContext.sharedInstance().configuration.gcmSenderID
// [END_EXCLUDE]
// Register for remote notifications
if #available(iOS 8.0, *) {
let settings: UIUserNotificationSettings =
UIUserNotificationSettings(forTypes: [.Alert, .Badge, .Sound], categories: nil)
application.registerUserNotificationSettings(settings)
application.registerForRemoteNotifications()
} else {
// Fallback
let types: UIRemoteNotificationType = [.Alert, .Badge, .Sound]
application.registerForRemoteNotificationTypes(types)
}
// [END register_for_remote_notifications]
// [START start_gcm_service]
let gcmConfig = GCMConfig.defaultConfig()
gcmConfig.receiverDelegate = self
GCMService.sharedInstance().startWithConfig(gcmConfig)
// [END start_gcm_service]
return true
}
func subscribeToTopic() {
// If the app has a registration token and is connected to GCM, proceed to subscribe to the
// topic
if(registrationToken != nil && connectedToGCM) {
GCMPubSub.sharedInstance().subscribeWithToken(self.registrationToken, topic: subscriptionTopic,
options: nil, handler: {(NSError error) -> Void in
if (error != nil) {
// Treat the "already subscribed" error more gently
if error.code == 3001 {
print("Already subscribed to \(self.subscriptionTopic)")
} else {
print("Subscription failed: \(error.localizedDescription)");
}
} else {
self.subscribedToTopic = true;
NSLog("Subscribed to \(self.subscriptionTopic)");
}
})
}
}
// [START connect_gcm_service]
func connectGcmService( application: UIApplication) {
// Connect to the GCM server to receive non-APNS notifications
GCMService.sharedInstance().connectWithHandler({
(NSError error) -> Void in
if error != nil {
print("Could not connect to GCM: \(error.localizedDescription)")
} else {
self.connectedToGCM = true
print("Connected to GCM")
// [START_EXCLUDE]
self.subscribeToTopic()
// [END_EXCLUDE]
}
})
}
// [END connect_gcm_service]
// [START disconnect_gcm_service]
func applicationDidEnterBackground(application: UIApplication) {
GCMService.sharedInstance().disconnect()
// [START_EXCLUDE]
self.connectedToGCM = false
// [END_EXCLUDE]
}
// [END disconnect_gcm_service]
// [START receive_apns_token]
public func receiveApnsToken( application: UIApplication, deviceToken: NSData ) {
// [END receive_apns_token]
// [START get_gcm_reg_token]
// Create a config and set a delegate that implements the GGLInstaceIDDelegate protocol.
let instanceIDConfig = GGLInstanceIDConfig.defaultConfig()
instanceIDConfig.delegate = self
// Start the GGLInstanceID shared instance with that config and request a registration
// token to enable reception of notifications
GGLInstanceID.sharedInstance().startWithConfig(instanceIDConfig)
registrationOptions = [kGGLInstanceIDRegisterAPNSOption:deviceToken,
kGGLInstanceIDAPNSServerTypeSandboxOption:true]
GGLInstanceID.sharedInstance().tokenWithAuthorizedEntity(gcmSenderID,
scope: kGGLInstanceIDScopeGCM, options: registrationOptions, handler: registrationHandler)
// [END get_gcm_reg_token]
}
// [START receive_apns_token_error]
public func receiveApnsTokenError( application: UIApplication, error: NSError ) {
print("Registration for remote notification failed with error: \(error.localizedDescription)")
// [END receive_apns_token_error]
let userInfo = ["error": error.localizedDescription]
NSNotificationCenter.defaultCenter().postNotificationName(
registrationKey, object: nil, userInfo: userInfo)
}
// [START ack_message_reception]
func ackMessageReception( application: UIApplication, userInfo: [NSObject : AnyObject]) {//, fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
print("Notification received: \(userInfo)")
// This works only if the app started the GCM service
GCMService.sharedInstance().appDidReceiveMessage(userInfo);
...
}
func application( application: UIApplication,
didReceiveRemoteNotification userInfo: [NSObject : AnyObject],
fetchCompletionHandler handler: (UIBackgroundFetchResult) -> Void) {
print("Notification received: \(userInfo)")
// This works only if the app started the GCM service
GCMService.sharedInstance().appDidReceiveMessage(userInfo);
// Handle the received message
// Invoke the completion handler passing the appropriate UIBackgroundFetchResult value
// [START_EXCLUDE]
NSNotificationCenter.defaultCenter().postNotificationName(messageKey, object: nil,
userInfo: userInfo)
handler(UIBackgroundFetchResult.NoData);
// [END_EXCLUDE]
}
// [END ack_message_reception]
func registrationHandler(registrationToken: String!, error: NSError!) {
if (registrationToken != nil) {
self.registrationToken = registrationToken
print("Registration Token: \(registrationToken)")
self.subscribeToTopic()
let userInfo = ["registrationToken": registrationToken]
NSNotificationCenter.defaultCenter().postNotificationName(
self.registrationKey, object: nil, userInfo: userInfo)
} else {
print("Registration to GCM failed with error: \(error.localizedDescription)")
let userInfo = ["error": error.localizedDescription]
NSNotificationCenter.defaultCenter().postNotificationName(
self.registrationKey, object: nil, userInfo: userInfo)
}
}
// [START on_token_refresh]
public func onTokenRefresh() {
// A rotation of the registration tokens is happening, so the app needs to request a new token.
print("The GCM registration token needs to be changed.")
GGLInstanceID.sharedInstance().tokenWithAuthorizedEntity(gcmSenderID,
scope: kGGLInstanceIDScopeGCM, options: registrationOptions, handler: registrationHandler)
}

Answer 1

Based on the docs, If registration fails, the client app is recommended to retry. In cases where GCM is not essential to the client app's functioning, the app could ignore the registration error and try to register again the next time it starts. Otherwise, it should retry the registration operation using exponential back-off (the client app should wait twice the previous amount of time before retrying). Once your client app has a registration token, it can receive messages through the GCM APNs interface.
To handle cases where registration token has been refreshed, the GGLInstanceIDDelegate protocol declares an onTokenRefresh method that is called when the system determines that tokens need to be refreshed.
func onTokenRefresh() {
// A rotation of the registration tokens is happening, so the app needs to request a new token.
print("The GCM registration token needs to be changed.")
GGLInstanceID.sharedInstance().tokenWithAuthorizedEntity(gcmSenderID,
scope: kGGLInstanceIDScopeGCM, options: registrationOptions, handler: registrationHandler)
}