CFDictionary returns null

I'm attempting to use Core Foundation for the first time and I must be missing something. I am attempting to use NSObjects as my keys and values for a CFMutableDictionaryRef.

I have the following test app:

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSString* key = @"testKey";
    NSObject* item = [[NSObject alloc] init];

    const CFDictionaryKeyCallBacks keyCB = kCFTypeDictionaryKeyCallBacks;
    const CFDictio开发者_如何学运维naryValueCallBacks valCB = kCFTypeDictionaryValueCallBacks;

    CFMutableDictionaryRef dict = CFDictionaryCreateMutable(NULL, 0, &keyCB, &valCB);
    CFDictionaryAddValue(dict, item, key);
    NSLog(@"[CH] added = %@", CFDictionaryGetValue(dict, key));
    NSLog(@"[CH] size = %ld", CFDictionaryGetCount(dict));


}

The output:

2011-07-14 16:47:40.568 TestCoreFoundation[61343:903] [CH] added = (null) 2011-07-14 16:47:40.578 TestCoreFoundation[61343:903] [CH] size = 1

You have the call to CFDictionaryAddValue backwards. It's dict, key, and then value:

CFDictionaryAddValue(dict, key, item);

Other than that, it looks fine.

Hope that helps.