I need to know when a sharer has been authorized (to change some UI) and it looks like there's a SharerDelegate sharerAuthDidFinish method which (I think) I implemented, but it doesn't get called.
Anyone?
Thanks!
In SHKSharer.m, there is the following code:
- (void)authDidFinish:(BOOL)success
{
[[NSNotificationCenter defaultCenter] postNotificationName:#"SHKAuthDidFinish" object:self userInfo:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:success] forKey:#"success"]];
if ([self.shareDelegate respondsToSelector:#selector(sharerAuthDidFinish:success:)]) {
[self.shareDelegate sharerAuthDidFinish:self success:success];
}
}
So you can listen for the notification in whatever class needs to know like such:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(sharerAuthorized:) name:#"SHKAuthDidFinish" object:nil];
and then implement a method like:
- (void)sharerAuthorized:(NSNotification *)notification {
//check for success and type of sharer
//do whatever you need to do once it is authorized
}
Related
I'm using the next code to know when a device is plugged in:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
//code...
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(accesoryChanged:) name:EAAccessoryDidConnectNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(accesoryChanged:) name:EAAccessoryDidDisconnectNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(accesoryChanged:) name:UIScreenDidConnectNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(accesoryChanged:) name:UIScreenDidDisconnectNotification object:nil];
EAAccessoryManager *accessoryManager = [EAAccessoryManager sharedAccessoryManager];
[accessoryManager registerForLocalNotifications];
}
- (void)accesoryChanged:(NSNotification*)note;
{
if(note.name == EAAccessoryDidConnectNotification)
{
EAAccessory* accessory = [note.userInfo objectForKey:EAAccessoryKey];
//code...
}
else if(note.name == EAAccessoryDidDisconnectNotification)
{
EAAccessory* accessory = [note.userInfo objectForKey:EAAccessoryKey];
//code...
}
}
And with:
accessory.name
I can get the device's name, but I couldn't find a way to know what kind of device is (i.e: a controller or a HDMI adapter).
Is there any way to get this information?
Thanks in advance.
The EAAccessory object has properties for the manufacturer, modelNumber, and serialNumber. You can also look at the array of protocolStrings to get an idea of the device's capabilities.
When deciding whether to connect to an accessory, you should use the accessory’s declared protocols to make your determination. The protocols associated with an accessory indicate the types of data the accessory is capable of processing. You may use other properties to help you decide whether or not to connect to an accessory but the list of protocols should be the key factor you consider.
Is there a way onto the iPhone for an object to send a message without a specific receiver object, and into another object, listen to such messages, that could come with objects (parameters), and do what is needed ?
I searched around NSNotification but I don't see what I should do.
Objects that want to be notified need to register to receive notifications with the notification center. Thereafter, when a notification is posted to the notification center, the notification center will check it against all the registered filters, and the corresponding action will be taken for each matching filter.
A "filter" in this case is the pair of (notification name, notification object). A nil object in the filter is equivalent to any object (the notification object is ignored in matching). The name is required.
Example:
/* Subscribe to be sent -noteThis:
* whenever a notification named #"NotificationName" is posted to the center
* with any (or no) object. */
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self selector:#selector(noteThis:)
name:#"NotificationName"
object:nil];
/* Post a notification. */
[nc postNotificationName:#"NotificationName" object:self userInfo:someDict];
/* Handle a notification. */
- (void)noteThis:(NSNotification *)note
{
id object = [note object];
NSDictionary *userInfo = [note userInfo];
/* take some action */
}
There is a more modern API using queues and blocks, but I find the old API easier to illustrate and explain.
Basically, you post a notification (NSNotification) to the shared class, NSNotificationCenter. Here's an example:
#define kNotificationCenter [NSNotificationCenter defaultCenter]
#define kNotificationToSend #"a notification name as a string"
//... Post the notification
[kDefaultCenter postNotificationNamed:knotificationToSend withObject:nil];
Any class that wants to listen, adds itself as an observer to the notifcation center. You must remove the observer as well.
[kNotificationCenter addObserver:self selector:#selector(methodToHandleNotification) object:nil];
//... Usually in the dealloc or willDisappear method:
[kNotificationCenter removeObserver:self];
You can do more with the notification center. See the NSNotificationCenter documentation fr complete reference.
I think NSNotification is the message object itself, to send to listen to what is sent try NSNotificationCenter. It has a singleton object, so to send the message:
NSNotification *notificationObj;
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center postNotification:notificationObj];
And the other class listen to with:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(method:) object:nil];
Make sure that class has method: method. You can have a single parameter, which is an NSNotification object that is sent earlier. The NSNotification object has [notificationObj object which you can get as a piece of data sent by the sender class. Alternatively, you might use [notificationObj userInfo] if you want it to be more structured.
you can initialise notificationObj and tailor it with the message that you'd want. More information on NSNotificationCenter, you can find it
http://developer.apple.com/library/ios/#documentation/Cocoa/Reference/Foundation/Classes/NSNotificationCenter_Class/Reference/Reference.html#//apple_ref/occ/cl/NSNotificationCenter
or for more information about NSNotification itself
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSNotification_Class/Reference/Reference.html
I make a call to a web service, passing a parameter and then register an observer in a viewcontroller class (to notify completion of download) :
[self callWebservice:parameter1];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(dataDownloadComplete:) name:OP_DataComplete object:nil];
and then post a notification in my parser class:
-(void)connectionDidFinishLoading:(NSURLConnection *)connection method of the parser class. [[NSNotificationCenter defaultCenter] postNotificationName:OP_DataComplete object:nil];
In the callback method dataDownloadComplete: i would like to call the same web service again several times.
-(void)dataDownloadComplete
{
if([anArray objectAtindex:N]<10)
{
[self callWebservice:parameterN];
NSLog(#"This is getting called everytime (9 times)");
[self writeintoDatabase];
N++;
}
}
But the problem is that i want to write into a database what data i download from the service. The DB writing happens for 'parameter1' call strangely, and goes on for the others but not for parameter9(which i need as well). Note the Log is called all 9 times though. The writeintoDatabase code is perfect. Please help. Thanks in advance.
So I have this function inside NotificationManager class.
-(void) postNotificationForClassName:(NSString*)className withObjects:(NSArray*)objects withError:(BOOL)withError
{
notificationName = [NSString stringWithFormat:#"didLoad%#",className];
[[NSNotificationCenter defaultCenter]
postNotificationName:notificationName object:self];
}
now, let's say I have 2 classes , A and B.
from A's method foo() I do the following:
[[NotificationManager sharedManager]
postNotificationForClassName:#"A" withObjects:objects withError:NO]
from B's method goo() I do the following:
[[NotificationManager sharedManager]
postNotificationForClassName:#"A" withObjects:objects withError:NO]
Now, I'm curious what should I do in case I want to listen only to notifications being posted from Class A.
Is this suppose to work ?
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(didLoadData:)
name:#"didLoadA" object:classAObject];
Cause I'm assuming that when I'm calling
[[NSNotificationCenter defaultCenter]
postNotificationName:notificationName object:self];
and I pass the "self", then the "self" will be the NotificationManager and not the class A or B that called the NotificationManager method.
Am I right or wrong here ? and if I'm right, is there a way to do what I want to accomplish?
Thanks!
self is a special variable, always referring to the object that received the message currently being handled. In NotificationManager's -postNotificationForClassName:withObjects:objectswithError:withError:, self is a NotificationManager (or descendent). As for self in the call to -addObserver:..., it depends on what method the call occurs in.
As you've noticed, -addObserver:... lets you monitor notifications from specific objects. You could use this to monitor messages from As if you use the class A as the object:
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(didLoadData:)
name:#"didLoadA" object:[A class]];
However, you'll also need to change the notification sender in -postNotificationForClassName:withObjects:objectswithError:withError:.
-(void)postNotificationForClassName:(NSString*)className
withObjects:(NSArray*)objects
withError:(BOOL)withError
from:(id)sender
{
notificationName = [NSString stringWithFormat:#"didLoad%#",className];
[[NSNotificationCenter defaultCenter]
postNotificationName:notificationName object:[sender class]];
}
I am trying to pass an NSDictionary form a UIView to a UIViewController using NSNotificationCenter. The dictionary works fine at the time the notification is posted, but in the receiving method I am unable to access any of the objects in the dictionary.
Here is how I am creating the dictionary and posting the notification...
itemDetails = [[NSDictionary alloc] initWithObjectsAndKeys:#"Topic 1", #"HelpTopic", nil];
[[NSNotificationCenter defaultCenter] postNotificationName:#"HotSpotTouched" object:itemDetails];
In the UIViewController I am setting the observer...
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(hotSpotMore:)
name:#"HotSpotTouched"
object:nil];
For testing purposes hotSpotMore looks like this...
- (void)hotSpotMore:(NSDictionary *)itemDetails{
NSLog(#"%#", itemDetails);
NSLog(#"%#", [itemDetails objectForKey:#"HelpTopic"]);
}
The first NSLog works fine displaying the contents of the dictionary. The second log throws the following exception...
[NSConcreteNotification objectForKey:]: unrecognized selector sent to instance 0x712b130
I don't understand why I cannot access any objects in the passed dictionary.
Thanks in advance for any help.
John
The first NSLog works fine displaying
the contents of the dictionary. The
second log throws the following
exception...
The program tries to trick you, it just looks like it is your dictionary because your dictionary is inside the notification. From the exception you can see that your object actually is from a class named NSConcreteNotification.
This is because the argument of a notification-method is always a NSNotification-object.
this will work:
- (void)hotSpotMore:(NSNotification *)notification {
NSLog(#"%#", notification.object);
NSLog(#"%#", [notification.object objectForKey:#"HelpTopic"]);
}
just as a hint: the object is usually the object which sends the notification, you should send your NSDictionary as userInfo.
I think it would improve your code if you would do it like this:
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center postNotificationName:#"HotSpotTouched" object:self userInfo:itemDetails];
- (void)hotSpotMore:(NSNotification *)notification {
NSLog(#"%#", notification.userInfo);
NSLog(#"%#", [notification.userInfo objectForKey:#"HelpTopic"]);
}
The object parameter is used to distinguish between the different objects that can send a notification.
Let’s say you have two different HotSpot objects that can both send the notification. When you set the object in addObserver:selector:name:object: you can add a different observer for each of the objects. Using nil as the object parameter means that all notifications should be received, regardless of the object that did send the notification.
E.g:
FancyHotSpot *hotSpotA;
FancyHotSpot *hotSpotB;
// notifications from hotSpotA should call hotSpotATouched:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(hotSpotATouched:) name:#"HotSpotTouched"
object:hotSpotA]; // only notifications from hotSpotA will be received
// notifications from hotSpotB should call hotSpotBTouched:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(hotSpotBTouched:) name:#"HotSpotTouched"
object:hotSpotB]; // only notifications from hotSpotB will be received
// notifications from all objects should call anyHotSpotTouched:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(anyHotSpotTouched:) name:#"HotSpotTouched"
object:nil]; // nil == “any object”, so all notifications with the name “HotSpotTouched” will be received
- (void)hotSpotATouched:(NSNotification *)n {
// only gets notification of hot spot A
}
- (void)hotSpotBTouched:(NSNotification *)n {
// only gets notification of hot spot B
}
- (void)anyHotSpotTouched:(NSNotification *)n {
// catches all notifications
}
This is the best way to pass your dictionary data with NSNotification.
Post Notification :
[[NSNotificationCenter defaultCenter] postNotificationName:#"Put Your Notification Name" object:self userInfo:"Pass your dictionary name"];
Add Observer for Handle the Notification.
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(mydictionaryData:) name:#"Put Your Notification Name" object:nil];
Put Notification Handler method.
- (void)mydictionaryData::(NSNotification*)notification{
NSDictionary* userInfo = notification.userInfo;
NSLog (#"Successfully received test notification! %#", userInfo);}
I hope, this solution will help you
The method Matthias is talking about and the one I think you should be using is
postNotificationName:object:userInfo:
Where object is the sender and userInfo is your dictionary.