With iOS 5 and storyboarding, what is the best way to present a view when the user enters the app after having received a localnotification?
I have read that using the NSNotificationCenter is the way to do it but is that also so with storyboarding and segues?
This is exactly how I implemented it. In the AppDelegate's didFinishLaunchingWithOptions: method, I did the following:
UILocalNotification *notification =
[launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];
[self application:application didReceiveLocalNotification:notification];
I did this so that I could keep logic in a single place. In the didreceiveLocalNotification: method, I then used the NSNotificationCenter:
// Let another view handle the display
NSNotificationCenter * nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:#"SHOW_VERSE"
object:self
userInfo:notification.userInfo];
The view that handles the display is the first UIViewController for the Storyboard. In that class, in the viewDidLoad method:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(receivedLocalNotification:)
name:#"SHOW_VERSE"
object:nil];
This works very well for me. Hope it helps.
Related
How to dismiss popover when application enters in background?
You can do this using the delegate method in appdelegate.m file
- (void)applicationDidEnterBackground:(UIApplication *)application
{
//put your dissmiss popover code here
}
it is better to register your controller for UIApplicationDidEnterBackgroundNotification or UIApplicationWillResignActiveNotification and dismiss it whenever your app goes to background, this will make your life quite easier i feel.
registering for notification in your viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(myMethod)
name:UIApplicationDidEnterBackgroundNotification object:nil];
implement the method and
-(void)myMethod{
// dismiss popview here
}
finally un-register from the notification in your view controller
-(void)dealloc{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
Send an NSNotification in your app delegate's willResignActive method, and listen for it in your view controller that contains the popup, and have it dismiss said popover when the notification is received.
try this
- (void)applicationDidEnterBackground:(UIApplication *)application
{
//[popover dissmissPopoverAnimated:YES];
}
I would like to know how I can call the selector which is in another class when notification is posted.I am on tabbarcontroller.
The FirstViewController, SecondViewController are tab bar items
Inside `FirstViewController` I have the following
-(void)viewdidload
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(productPurchased:) name:kProductPurchasedNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector: #selector(productPurchaseFailed:) name:kProductPurchaseFailedNotification object: nil];
}
- (void)productPurchased:(NSNotification *)notification {
[NSObject cancelPreviousPerformRequestsWithTarget:self];
NSString *productIdentifier = (NSString *) notification.object;
NSLog(#"Purchased: %#", productIdentifier);
[appDelegate.myDownloadablePoemsArray addObject:productIdentifier];
[self.tabBarController setSelectedIndex:3];
}
- (void)productPurchaseFailed:(NSNotification *)notification {
[NSObject cancelPreviousPerformRequestsWithTarget:self];
SKPaymentTransaction * transaction = (SKPaymentTransaction *) notification.object;
if (transaction.error.code != SKErrorPaymentCancelled) {
UIAlertView *alert = [[[UIAlertView alloc] initWithTitle:#"Error!"
message:transaction.error.localizedDescription
delegate:nil
cancelButtonTitle:nil
otherButtonTitles:#"OK", nil] autorelease];
[alert show];
}
}
The above code is working fine. Now what the issue is, I want to call the same selector method from my another view say for example I have a view controller named SecondViewController, in that I am adding the same notification observer.
but the selector method is not called in the FirstViewController.
Inside SecondViewController I have the following
-(void)viewdidload
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(productPurchased:) name:kProductPurchasedNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector: #selector(productPurchaseFailed:) name:kProductPurchaseFailedNotification object: nil];
}
But I want to call the selecor methods from FirstViewController;
Please let me know , is that possible ? And how can I do that?
Thanks a lot
in the SecondViewController change the self as observer to the pointer of the FirstViewController, because the instance of FirsViewController has the methods.
inside SecondViewController.m you must use these lines:
- (void)viewdidload {
[[NSNotificationCenter defaultCenter] addObserver:firstViewController selector:#selector(productPurchased:) name:kProductPurchasedNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:firstViewController selector: #selector(productPurchaseFailed:) name:kProductPurchaseFailedNotification object: nil];
}
BUT! AND THIS IS THE POINT.
if the FirstViewController is already a valid and loaded view controller in the memory with the methods as you've mentioned above, and it is an observer already for these notifications in the NSNotificatioCenter, you don't need to add again it to the NSNotificationCenter because the FirstViewController can receive and will receive the desired notification still. (it is just not shown, because an other view controller covers it.)
if the FirstViewController is not exists yet when the SecondViewController is, you cannot reach any instance method called from an another class because the FirstViewController was not instantiated before, and you cannot add it to the NSNotificationCenter as well.
CONCLUSION
it would be better to isolate the purchase callbacks into a third class what you can use for every independent view controller, according to the spirit of the OOP and MVC.
If your view controllers are the roots of tab-bar controllers, once they are loaded the first time, they stay around unless manually replaced.
Thus, when you install the notification handler in the first controller, unless you remove the notification handler, it will still get them, even when the second controller is onscreen.
Now, it may get unloaded due to memory pressure, or by the custom tab-bar-controller code. However, it's highly unusual for a tab-bar controller to deallocate one of its view controllers, so your installed notification handlers will be around until you cancel them.
In fact, if both view controllers register for the notifications, then they will both get them.
You are registering in viewDidLoad so the first one will get registered immediately, as it will be loaded and displayed as the initial controller. It will continue to receive those notifications.
When the second one loads, it will also register. Now both view controllers are receiving the notifications. When you go back to the first view controller, they will both still be getting the notifications.
I'm trying to get my head around NSNotificationCenter. If I have something like this in my App Delegate:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(something:)
name:#"something"
object:nil];
-----
-(void)something:(NSNotification *) notification
{
// do something
}
Can I somehow watch this in another view controller? In my case, I'd like to watch it in a view controller with a table, and then reload the table when a notification is received. Is this possible?
Yes you can do it like this:
In class A : post the notification
[[NSNotificationCenter defaultCenter] postNotficationName:#"DataUpdated "object:self];
In class B : register first for the notification, and write a method to handle it.
You give the corresponding selector to the method.
//view did load
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(handleUpdatedData:) name:#"DataUpdated" object:nil];
-(void)handleUpdatedData:(NSNotification *)notification {
NSLog(#"recieved");
}
Yes you can that is the whole purpose of NSNotification, you just have to add the View Controller you want as an observer exactly the same way you did on your App Delegate, and it will receive the notification.
You can find more information here: Notification Programming
Of course it's possible, that's the whole point of notifications. Using addObserver:selector:name:object: is how you register to receive notifications (you should do this in your table view controller), and you can use postNotificationName:object:userInfo: to post a notification from any class.
Read Notofication Programming Topics for more info.
You can register to observe notifications in as many classes as you like. You simply need to "rinse and repeat". Include the code to register as an observer in your view controller (perhaps in viewWillAppear:) and then reload the tableView from your method:
- (void)viewWillAppear:(BOOL)animated {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(something:) name:#"something" object:nil];
}
-(void)something:(NSNotification *) notification
{
[self.tableView reloadData];
}
It's also a good idea to de-register the view controller once you no longer need the notifications:
- (void)viewWillDisappear:(BOOL)animated {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
You should just add that as an Observer and give a different selector method if you want that viewController to behave differently when that notification is posted.
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(somethingOtherThing:)
name:#"something"
object:nil];
-(void)somethingOtherThing:(NSNotification *) notification
{
// do something
}
I'm trying to pass an object between 2 VCs, from a popover to the detail view of split view controller.
I think I need to use NSNotificationCenter.
I tried this but can't seem to get it to work.
In didSelectRow of popover
[[NSNotificationCenter defaultCenter] postNotificationName:#"PassObject" withObject:objectToPass];
In detail VC
- (void) didReceiveNotificationPassObject:(NSNotification*)notification
{
YourObjectClass *theObject = (YourObjectClass*)notification.object;
}
- (void)viewDidLoad
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(didReceiveNotificationPassObject:) name:#"PassObject" object:nil];
}
Probably just a typo when entering the question but in the first line where you post the notification
[[NSNotificationCenter defaultCenter] postNotificationName:#"PassObject" withObject:objectToPass];
the method signature is wrong - it should be 'object:objectToPass' not 'withObject:objectToPass'. The line you have there will compile with a warning and crash at runtime.
Aside from that all the logic seems fine.
What is the problem you are facing? Does didReceiveNotificationPassObject: hit? If it doesn't, you could verify that viewDidLoad executes before didSelectRow.
Use [[NSNotificationCenter defaultCenter] postNotificationName:#"PassObject" object:objectToPass]; instead of [[NSNotificationCenter defaultCenter] postNotificationName:#"PassObject" withObject:objectToPass];
Also, don't forget to removeObserver in viewDidUnload.
HTH,
Akshay
A fast and easy solution to notify with multiple parameters is to call the notification it like this
[[NSNotificationCenter defaultCenter] postNotificationName:#"shareButton" object:#"camera"];
Where "camera" acts like your parameter. Then
- (void)shareButton:(id)sender
{
NSString *kindOf = [sender object];
if ([kindOf isEqualToString:#"camera"]) {
// Your code goes here
}
}
I have a tabbar application and let's say that I want to switch to the second tab and popup an alert at 12:00, even if my application is not running.
I got all the code for UILocalNotification working correctly, but then I thought that the best way to do that would be by posting a notification from the app delegate:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Add the tab bar controller's view to the window and display.
[window addSubview:tabBarController.view];
[window makeKeyAndVisible];
// Handle launching from a notification when the app is NOT running
UILocalNotification *localNotification = [launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];
if (localNotification) {
[tabBarController setSelectedIndex:1];
[[NSNotificationCenter defaultCenter] postNotificationName:#"AlertNotification" object:self];
}
return YES;
}
Then, in my SecondViewController.m, I have:
- (void)viewDidLoad {
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(popUpAlert:) name:#"AlertNotification" object:nil];
}
But this does not work. I suspect that the notification is sent while the viewDidLoad of the SecondViewController has not been called yet, right? Is it possible to work this out? And do you agree on my approach of using NSNotificationCenter in this case?
Thanks in advance.
I quickly created a test project and got it working by putting the notification registration in awakeFromNib (assuming SecondViewController is created in a xib file)
- (void)awakeFromNib {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(popUpAlert:) name:#"AlertNotification" object:nil];
}
I guess, you are right. It doesn't work because you are posting the notification before adding the view controller as observer for it.
Another approach would be to add a bool property to the app delegate to indicate whether the app has been started from the local notification.
The app delegate can be requested from anywhere in the app with [[UIApplication sharedApplication] delegate].
UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes: UIUserNotificationTypeAlert | UIUserNotificationTypeBadge categories:nil];
[[UIApplication shareApplication] registerUserNotificationSettings: settings];