unrecognized selector sent to instance

Question

I have an issue with selecting a method for a notification.

In the init I have definied this:

NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self selector:@selector(stopSyncIndicator:) name:IOS_STOP_SYNC_INDICATOR object:nil];

The method is definied though, both in header and same implementation:

-(void)stopSyncIndicator
{
    [indicator stopAnimating];
}

However when a different class is posting this notification:

NSNotification *note = [NSNotification notificationWithName:IOS_STOP_SYNC_INDICATOR object:nil];
[[NSNotificationCenter defaultCenter] postNotification:note];

The hell breaks loose:

[FTRecordViewController stopSyncIndicator:]: unrecognized selector sent to instance 0x8d3bc00
2013-11-18 13:47:06.994 [1835:70b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[FTRecordViewController stopSyncIndicator:]: unrecognized selector sent to instance 0x8d3bc00'
*** First throw call stack:
(
    0   CoreFoundation                      0x01bf75e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x018f88b6 objc_exception_throw + 44
    2   CoreFoundation                      0x01c94903 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275

Any idea what is going on here?

Possible duplicate of [How can I debug 'unrecognized selector sent to instance' error](https://stackoverflow.com/questions/25853947/how-can-i-debug-unrecognized-selector-sent-to-instance-error) — Cœur, Jul 08 '19 at 05:50

wattson12 · Accepted Answer · 2013-11-18T14:04:14.560

6

Your selector has a : indicating it will accept an argument, your implementation does not

either

@selector(stopSyncIndicator) //no :

or

-(void)stopSyncIndicator:(NSNotification *)notification //accept argument

would fix this

edited Nov 18 '13 at 14:04

answered Nov 18 '13 at 13:57

wattson12

11,176
2
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score 2 · Answer 2 · edited Nov 18 '13 at 14:18

You telling that the observer's selector has a parameter:

[nc addObserver:self selector:@selector(stopSyncIndicator:) name:IOS_STOP_SYNC_INDICATOR object:nil];`<br/>

and your selector doesn't have a parameter:

-(void)stopSyncIndicator

To fix, either remove the : from selector:@selector(stopSyncIndicator:) or set your method signature to:

-(void)stopSyncIndicator:(NSNotification *)notification

unrecognized selector sent to instance

2 Answers2