I'd like to reload a table view which is in another class called "WriteIt_MobileAppDelegate" from one of my other classes which is called "Properties". I've tried to do this via the NSNotificationCenter class - the log gets called but the table is never updated.
Properties.h:
[[NSNotificationCenter defaultCenter] postNotificationName:#"NameChanged"
object:[WriteIt_MobileAppDelegate class]
userInfo:nil];
WriteIt_MobileAppDelegate.m
-(void)awakeFromNib {
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(reloadItProperties:)
name:#"NameChanged" object:self];
}
- (void) reloadItProperties: (NSNotification *)notification {
NSLog(#"Reloading Data"); //this gets called
[[self navigationController] dismissModalViewControllerAnimated:YES];
[self.navigationController popToRootViewControllerAnimated:YES];
[self.tblSimpleTable reloadData];
[self.tblSimpleTable reloadSectionIndexTitles];
// but the rest doesn't
}
What am I doing wrong here?
Seems like you are using the object parameter wrong:
addObserver:selector:name:object:
notificationSender
The object whose
notifications the observer wants to
receive;
that is, only notifications
sent by this sender are delivered to
the observer. If you pass nil, the
notification center doesn’t use a
notification’s sender to decide
whether to deliver it to the observer.
Related
I have a view controller, when it's dissming with completion, I post a notfication, and in a subview which contained in another view controller, has added as a oberserve. But, when it tries to execute post notificaiton methode, exec_bad_access happend. what's wrong? The codes are:
BrandListByIdViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSNumber *bid = self.brands[indexPath.row][#"id"];
[self dismissViewControllerAnimated:YES completion:^{
[[NSNotificationCenter defaultCenter] postNotificationName:#"SelectedBrandId" object:nil];
}];
}
SearchNewProduct.h
#interface SearchNewProduct : UIView
#end
SearchNewProduct.m
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(didSelectedBrandId::) name:#"SelectedBrandId" object:nil];
}
}
- (void)didSelectedBrandId:(NSNotification *)notif{
NSLog(#"%s", __PRETTY_FUNCTION__);
}
Even I get rid of the userInfo, still bad access. I created a similar situation in another new project, it works fine.
I didn't realize that you were dealing with a UIView and not a UIViewController (should have read your question better). I think what is happening is that the View is receiving notifications even after being released. Make sure to call dealloc in your UIView and remove itself as an observer:
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
Also, put an NSLog in that UIView's initWithFrame method to see if it is being called more than once.
This question is very similar:
ios notifications to "dead" objects
Not sure if this is the reason, but when you add your view to the notification center, your selector is wrong:
selector:#selector(didSelectedBrandId::)
There should only be one colon. The entire line should be:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(didSelectedBrandId:) name:#"SelectedBrandId" object:nil];
Two colons indicates the method takes two arguments, but it only takes one.
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 am trying to post a notification without much success! I can do it
ok for the keyboard without issue but now am trying a custom one as
follows:
In my rootview I have this
.h
-(void) allowEdits:(NSNotification *)notification;
.m
//this section is run in method to present the passcode entry form
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(allowEdits:) name: #"PasscodeOK" object:nil];
PasscodeEntryViewController *vc = [[PasscodeEntryViewController alloc]
init];
[self presentModalViewController: vc animated:YES];
[vc release];
// and this is the response to the notification
-(void) allowEdits:(NSNotification *)notification {
NSLog(#"notification fired");
}
// in the vc instance I have this to notify passcode was ok
[[NSNotificationCenter defaultCenter]
postNotificationName:#"PasscodeOK" object:nil];
[self dismissView];
But the allowEdits never gets called?
Could you try posting your notification with:
[[NSNotificationCenter defaultCenter] postNotificationName:#"PasscodeOK" object:self];
As sender take the vc instance (self) instead of nil. Maybe that's solving your problem.