How to pass userInfo in NSNotification?

Question

I am trying to send some data using NSNotification but get stuck. Here is my code:

// Posting Notification
NSDictionary *orientationData;
if(iFromInterfaceOrientation == UIInterfaceOrientationLandscapeRight) {
    orientationData = [NSDictionary dictionaryWithObject:@"Right"
                                                  forKey:@"Orientation"];
}

NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter postNotificationName:@"Abhinav"
                                  object:nil
                                userInfo:orientationData];

// Adding observer
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(orientationChanged)
                                             name:@"Abhinav"
                                           object:nil];

Now how to fetch this userInfo dictionary in my selector orientationChanged?

score 97 · Accepted Answer · answered Oct 05 '10 at 07:15

97

You get an NSNotification object passed to your function. This includes the name, object and user info that you provided to the NSNotificationCenter.

- (void)orientationChanged:(NSNotification *)notification
{
    NSDictionary *dict = [notification userInfo];
}

answered Oct 05 '10 at 07:15

JustSid

25,168
7
79
97

Ok. And how to do this? Is it like: [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:self) name:@"Abhinav" object:nil];? – Abhinav Oct 05 '10 at 07:19
4

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:@"Abhinav" object:nil]; – JustSid Oct 05 '10 at 07:21
Any reason why one may be ending up with a nil dictionary? – NYC Tech Engineer Nov 10 '14 at 06:05
@NYCTechEngineer Because no user info has been provided – JustSid Nov 10 '14 at 07:49
@JustSid That's what I thought, but I ran the debugger, and saw that a dictionary was being passed as a parameter during the post. But on the receiving method, when I try to extract userInfo, nothing. – NYC Tech Engineer Nov 10 '14 at 08:31

score 23 · Answer 2 · edited Jul 04 '13 at 07:20

23

Your selector must have : to accept parameters.
e.g.

@selector(orientationChanged:)

then in the method declaration it can accept the NSNotification parameter.

edited Jul 04 '13 at 07:20

Navnath Godse

2,233
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answered Oct 05 '10 at 07:21

Manny

6,277
3
31
45

score 6 · Answer 3 · answered Mar 21 '13 at 05:04

You are posting the notification correctly. Please modify the Notification Observer like following.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:)
 name:@"Abhinav" object:nil];

- (void)orientationChanged:(NSNotification *)notification
{
    NSDictionary *dict = [notification userInfo];
}

I hope, this solution will work for you..

score 0 · Answer 4 · answered Apr 06 '16 at 10:11

0

In swift To get userinfo object

     let dict = notification.userInfo
     print(dict)

answered Apr 06 '16 at 10:11

amisha.beladiya

363
1
12

How to pass userInfo in NSNotification?

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