Wrong value from NSNumber to enum

Question

I'm sending a notification with enum inside:

[[NSNotificationCenter defaultCenter] postNotificationName:kNotificationTitle object:nil userInfo:@{[NSNumber numberWithInt:option2]:kNotificationName}];

And receiving it:

- (void)myAction:(NSNotification *)notification {
MyState myState = (MyState)[[[notification userInfo] objectForKey:kNotificationName] integerValue];

The problem is that myState has wrong value. When i print notification i get:

Printing description of notification:
NSConcreteNotification 0x123456 {name = notificationTitle; userInfo = {2 = notificationName;}}

But myState == option0.

Why it's happening like this?

EDIT:

typedef enum myStates {
  option0,
  option1,
  option2,
  option3
} MyState;

hope this will help u http://stackoverflow.com/questions/707512/what-is-a-typedef-enum-in-objective-c/17161563#17161563 — Rajneesh071, Sep 11 '13 at 07:46

score 1 · Answer 1 · answered Sep 11 '13 at 07:42

1

try to write your enum function like this:-

typedef enum myStates {
  option0 = 0,
  option1,
  option2,
  option3
} MyState;

and print both as individual like what output your notification has and what output your myState object has.

answered Sep 11 '13 at 07:42

D-eptdeveloper

2,430
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Yea right :) Overlooked that 0. Thanks, will accept in 8 minutes. – Nat Sep 11 '13 at 07:44
@Vive : great :) i'm glad that it helped you to overcome your issue. – D-eptdeveloper Sep 11 '13 at 07:46
Well it didn't. That was a bug indeed, but still i have the same problem and getting option0 as result :/ – Nat Sep 11 '13 at 07:47
Even better: use NS_ENUM ;) – HAS Sep 11 '13 at 19:01

score 1 · Answer 2 · answered Sep 11 '13 at 18:57

I wouldn't use NSNotification (as you've found out, no compile time check, and really cumbersome to use in many cases like this). Instead, a better alternative maybe to use an event bus like Tolo -- very easy to use and automatic removing of subscribers on dealloc. You would just write:

@interface EventStateChanged : NSObject
@property(nonatomic) MyState state;
@end

SUBSCRIBE(EventStateChanged)
{
MyState state = event.state;
    // Do something with state.
}

Check it out.

Interesting, I've never seen this. Will copy it somewhere and try to use later. Thanks for snippet. — Nat, Sep 13 '13 at 09:48

score 0 · Accepted Answer · answered Sep 11 '13 at 07:50

0

It looks like you got the value and key switched around.

The dictionary should be used like this: @{key:value}

Try this:

[[NSNotificationCenter defaultCenter] postNotificationName:kNotificationTitle object:nil userInfo:@{kNotificationName:[NSNumber numberWithInt:option2]}];

Hope it helps :)

answered Sep 11 '13 at 07:50

ThomasCle

6,792
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Indeed, this was the problem. – Nat Sep 11 '13 at 07:53

score 0 · Answer 4 · answered Sep 11 '13 at 07:52

0

User Info is a key => value dictionary:

userInfo:@{[NSNumber numberWithInt:option2]:kNotificationName}];

Here you have value => key. Try this:

@{kNotificationName:@{option2}]

answered Sep 11 '13 at 07:52

Grzegorz Krukowski

18,081
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Wrong value from NSNumber to enum

4 Answers4