Running code in the background in IOS - ios

Question

Firebase * ref = nil;
NSInteger iid = [[API sharedInstance] userid];
NSString * path = [NSString stringWithFormat: #"http://example.firebaseIO.com/user/%d/conversations", iid];
ref = [[Firebase alloc] initWithUrl:path];
if(ref) {
NSString * path = [NSString stringWithFormat: #"http://example.firebaseIO.com/conversations"];
Firebase * conv = [[Firebase alloc] initWithUrl: path];
[ref observeEventType:FEventTypeChildAdded withBlock:^(FDataSnapshot *snapshot) {
// name of conversation
NSString * name = snapshot.name;
Firebase * ref1 = [conv childByAppendingPath: name];
[ref1 observeSingleEventOfType:FEventTypeValue withBlock:^(FDataSnapshot *snapshot) {
if(snapshot.value != [NSNull null] && ![snapshot.value isKindOfClass: [NSString class]])
{
FDataSnapshot * chatsnapshot = [snapshot childSnapshotForPath: #"chats"];
NSInteger numChatMessages = chatsnapshot.childrenCount;
numberOfTotalChatMessages += numChatMessages;
NSMutableDictionary *m = [snapshot.value mutableCopy];
[m setValue: snapshot.name forKey: #"ref_name"];
NSInteger current_user = [[API sharedInstance] userid];
NSString * userpath = [NSString stringWithFormat: #"users/%d", current_user];
FDataSnapshot * usersnapshot = [snapshot childSnapshotForPath: userpath];
if(usersnapshot.value != [NSNull null] && ![usersnapshot.value isKindOfClass: [NSString class]])
{
NSDictionary * userdict = usersnapshot.value;
NSInteger numUserMessagesRead = [userdict[#"numOfMessages"] intValue];
numberOfMessagesRead += numUserMessagesRead;
if(numberOfTotalChatMessages > numberOfMessagesRead) {
[m setValue: #"true" forKey: #"bubble"];
}
}
[self.chats addObject: m];
NSNumber * index = [NSNumber numberWithInt: self.chats.count - 1];
[read setValue: index forKey: snapshot.name];
PLRightMenuViewController * rightPanel = (PLRightMenuViewController *) self.viewController.rightPanel;
[rightPanel.tableView reloadData];
self.numChats = numberOfTotalChatMessages - numberOfMessagesRead;
[[UIApplication sharedApplication] setApplicationIconBadgeNumber: self.numChats];
}
}];
}];
[ref observeEventType:FEventTypeChildChanged withBlock:^(FDataSnapshot *snapshot) {
NSString * name = snapshot.name;
Firebase * ref1 = [conv childByAppendingPath: name];
[ref1 observeSingleEventOfType:FEventTypeValue withBlock:^(FDataSnapshot *snapshot)
{
if(snapshot.value != [NSNull null] && ![snapshot.value isKindOfClass: [NSString class]])
{
numberOfTotalChatMessages += 1;
NSMutableDictionary *m = [snapshot.value mutableCopy];
[m setValue: snapshot.name forKey: #"ref_name"];
[m setValue: #"true" forKey: #"bubble"];
[self.chats addObject: m];
if([read objectForKey: snapshot.name])
{
NSInteger index = [[read objectForKey: snapshot.name] intValue];
[self.chats removeObjectAtIndex: index];
NSNumber * index1 = [NSNumber numberWithInt: self.chats.count - 1];
[read setValue: index1 forKey: snapshot.name];
}
self.numChats = numberOfTotalChatMessages - numberOfMessagesRead;
[[UIApplication sharedApplication] setApplicationIconBadgeNumber: self.numChats];
PLRightMenuViewController * rightPanel = (PLRightMenuViewController *) self.viewController.rightPanel;
[rightPanel.tableView reloadData];
}
}];
}];
}
I have the code above that basically checks for any new chat conversations using firebase and changes the application badge number. How can I run the code in the background of the app so that the application badge number is changed regardless of whether someone is currently using the app or not?
Basically, how can I run the code above in the background? What should I change in the Appdelegate?

Answer 1

You can't unless you cheat. Currently iOS or Apple respectively does not allow apps to go into the background with very few exceptions. Such as location services or playing audio.
Some cheat by pretending to play a sound or so.
Until now you would have to use push notifications in order to inform the app about incoming messages and update the badge.
Or ... wait for iOS 7 to be released. Assuming you've got a developer account, you can already access the docs and preview/beta resouces and prepare yourself until iOS 7 and the SDK etc. is GA.

Answer 2

// #interface
// Declare Private property
#property (nonatomic) UIBackgroundTaskIdentifier backgroundTask;
//#end
// ...
// Copy into
//#implementation
- (void)setupBackgrounding {
[[NSNotificationCenter defaultCenter] addObserver: self selector: #selector(appBackgrounding:)
name: UIApplicationDidEnterBackgroundNotification
object: nil];
[[NSNotificationCenter defaultCenter] addObserver: self selector: #selector(appForegrounding:)
name: UIApplicationWillEnterForegroundNotification
object: nil];
}
- (void)appBackgrounding: (NSNotification *)notification {
[self keepAlive];
}
- (void) keepAlive {
self.backgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
[[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];
self.backgroundTask = UIBackgroundTaskInvalid;
[self keepAlive];
}];
}
- (void)appForegrounding: (NSNotification *)notification {
if (self.backgroundTask != UIBackgroundTaskInvalid) {
[[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];
self.backgroundTask = UIBackgroundTaskInvalid;
}
}

Answer 3

You can do it with Push notification here is a great explanation about it.
example http://www.raywenderlich.com/32960/apple-push-notification-services-in-ios-6-tutorial-part-1
Note: you need one APNS which will notify your application.
In iOS7 come with feature with fetchAPI which will allow you to work on background but please note it not grantee that your application will run on background as system will decide when to allow application to run on background.
In iOS7 there is also one more thing call silent-Push notification which will allow you to update your view while notification come it means if your application in background and notification come you can change application badge number in background.

Answer 4

You need to use Apple Push Notification services, commonly abbreviated as APNs.

Answer 5

You can use these methods, to run background task for some more time..
- (UIBackgroundTaskIdentifier)beginBackgroundTaskWithExpirationHandler:(void(^)(void))handler NS_AVAILABLE_IOS(4_0);
- (void)endBackgroundTask:(UIBackgroundTaskIdentifier)identifier NS_AVAILABLE_IOS(4_0);
- (BOOL)setKeepAliveTimeout:(NSTimeInterval)timeout handler:(void(^)(void))keepAliveHandler NS_AVAILABLE_IOS(4_0);
- (void)clearKeepAliveTimeout NS_AVAILABLE_IOS(4_0);
- (void)getDataFromServer
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self beginBackgroundUpdateTask];
NSURLResponse * response = nil;
NSError * error = nil;
NSData * responseData = [NSURLConnection sendSynchronousRequest: request returningResponse: &response error: &error];
// Do something with the result
[self endBackgroundUpdateTask];
});
}
- (void) beginBackgroundUpdateTask
{
self.backgroundUpdateTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
[self endBackgroundUpdateTask];
}];
}
- (void) endBackgroundUpdateTask
{
[[UIApplication sharedApplication] endBackgroundTask: self.backgroundUpdateTask];
self.backgroundUpdateTask = UIBackgroundTaskInvalid;
}
Further more if you want to keep alive your application you can use this:-
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store
// enough application state information to restore your application to its current state in case
// it is terminated later.
//
// If your application supports background execution,
// called instead of applicationWillTerminate: when the user quits.
if ([application respondsToSelector:#selector(setKeepAliveTimeout:handler:)])
{
[application setKeepAliveTimeout:600 handler:^{
DDLogVerbose(#"KeepAliveHandler");
// Do other keep alive stuff here.
}];
}
}
It might help you..
And in iOS 7 there may be better ways to do that...