NSMutableDictionary "unrecognized selector sent to instance"

iphone nsmutabledictionary
Konobi picture Konobi · Dec 8, 2011 · Viewed 6.9k times · Source 
    -(void)saveDictionary:(int)counter
    {
        NSString *path=[[NSBundle mainBundle] pathForResource:@"Data" ofType:@"plist"];
        NSString *test = [NSString stringWithFormat:@"%d", counter];
        [theDictionary setObject:test forKey:@"Counter"]; <---- Error
        [theDictionary writeToFile:path atomically:YES];
    }

    - (void)applicationDidEnterBackground:(UIApplication *)application
    {
        [self saveDictionary:[_viewController counter]];
    }

Error: 

-[NSCFString setObject:forKey:]: unrecognized selector sent to instance
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFString setObject:forKey:]: unrecognized selector sent to instance

I can Load the value for Key "Counter" from plist. If I want to save the new value for same key "Counter" ... Error. Need Help, spent hours.

bye

Here is the Code to initialize theDictionary:

-(void)initDictionary {
    if (theDictionary == nil) {
        NSString *path=[[NSBundle mainBundle] pathForResource:@"Data" ofType:@"plist"];
        theDictionary = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
        theString = [theDictionary objectForKey:@"Counter"];
    }
}

Found it! 

theString = [[NSString alloc] initWithFormat:[theDictionary objectForKey:@"Counter"]];

Thanks All!

Answer

Mark Adams picture Mark Adams · Dec 8, 2011

This is because the object stored in theDictionary is actually an NSString and NSString doesn't contain a method called -setObject:forKey. Check your code for any places where theDictionary is being assigned and be sure that is actually an NSMutableDictionary.

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