无法访问时本地通知，并且应用程序在后台

Question

Goal is to notify end user about reachability changed when app is in background.

Broadcasting approach NSNotificationCenter not working in background. second approach i tried beginBackgroundTaskWithExpirationHandler in applicationDidEnterBackground but associated issue with it:

a) Time limitation of 10 min

b) i calling a end loop for detecting the reachability state which run on main thread and in result it choke the UI. Code:-

-(void)applicationDidEnterBackground:(UIApplication *)application
{
    NSLog(@"Application entered background state.");
    // bgTask is a property of the class
    if (isUserLogin) {
    NSAssert(self.bgTask == UIBackgroundTaskInvalid, nil);

    bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
        dispatch_async(dispatch_get_current_queue(), ^{
            [application endBackgroundTask:self.bgTask];
            self.bgTask = UIBackgroundTaskInvalid;
        });
    }];

    dispatch_async(dispatch_get_current_queue(), ^{
        while ([application backgroundTimeRemaining] > 1.0) {
            curReach = [[utilities sharedUtility]reachabilityChanged];
            NetworkStatus netStatus = [curReach currentReachabilityStatus];
            NSLog(@"-----------back ground task------------");
            if (netStatus == ReachableViaWWAN || netStatus == ReachableViaWiFi) {
                //isNetworkMessagePopup = YES;
            }
            else{
//                if (isNetworkMessagePopup) {
//                    isNetworkMessagePopup = NO;
                    UILocalNotification *localNotif = [[UILocalNotification alloc] init];
                    if (localNotif) {
                        localNotif.alertBody = FORMAT_UNABLE_TO_CONNECT_SERVER_DUE_TO_NO_INTERNET;
                        localNotif.alertAction = NSLocalizedString(@"Read Message", nil);
                        localNotif.soundName = @"pushNotification.caf";
                        localNotif.repeatInterval = 5;
                        //localNotif.applicationIconBadgeNumber = 1;
                        [application presentLocalNotificationNow:localNotif];
                        [localNotif release];
                        break;
                //}
                }
            }
        }
        [application endBackgroundTask:self.bgTask];
        self.bgTask = UIBackgroundTaskInvalid;
    });
    }
}

Please suggest me is it possible to notify user in iOS whenever reachability changed and app in background state?

If yes then how can i achieve this.

Thanks.

Answer 1

You could possibly use the background fetch capability as described in the iOS App Programming Guide to check reach ability and post a local notification if the network is un available.

There is no guarantee of how often this will be called - probably in the order of every few minutes or longer - certainly not every few seconds.