NSMutableDictionary won't append

Question

I have an NSMutableDictionary like this:

<dict>
    <key>Dictionaries</key>
    <dict>
        <key>One</key>
        <dict>
            <key>Data</key>
            <data>
            qqqqqg==
            </data>
        </dict>
        <key>Two</key>
        <dict>
            <key>Data</key>
            <data>
            qqqqqg==
            </data>
        </dict>
    </dict>
</dict>

Which is essentially an [NSMutableDictionary] that has other children dictionaries, all using the same number of objects and keys. The problem is that when I try and add another dictionary in the the existing 'Dictionaries' it wipes out all the others. I've tried using several functions including, setObject: forKey:, setDictionary: forKey:, addEntriesFromDictionary:...

NSMutableDictionary* mainDictionary = [[NSMutableDictionary alloc] initWithDictionary:otherDictionary];
            dictionaries = [mainDictionary objectForKey:@"Dictionaries"];
            [dictionaries addEntriesFromDictionary:otherDictionary];

I must be doing something wrong, or not using the function correct. An example of how to append my dictionary with Three, Four, etc. would be very helpful. thanks.

Answer 1

When you make this call

NSMutableDictionary* mainDictionary = [[NSMutableDictionary alloc] initWithDictionary:otherDictionary];

the only mutable dictionary that you are guaranteed to get is the outer one (i.e. the mainDictionary). If objects inside otherDictionary are mutable, they would remain mutable; if the objects inside otherDictionary are immutable, they would remain immutable.

It appears that the otherDictionary that you are passing to initWithDictionary: has been constructed from a property list. If this is the case, you can force all its containers to be mutable by passing NSPropertyListMutableContainers to the propertyListWithData:options:format:error: method, like this:

NSMutableDictionary *otherDictionary = [NSPropertyListSerialization
    propertyListWithData:myData
                 options:NSPropertyListMutableContainers
                  format:NULL
                   error:NULL
];