Question

I’m storing a bunch of data in a .plist file (in the application documents folder), and it’s structured like this:

Dictionary {
    "description" = "String Value",
    "sections" = Array (
        Array (
            Number,
            ...
            Number
        ),
        Array (
            Number,
            ...
            Number
        )
    ),
    "items" = Array (
        Array (
            Number,
            ...
            Number
        ),
        Array (
            Number,
            ...
            Number
        )
    )
}

If I just retrieve it with
NSMutableDictionary *d = [[NSMutableDictionary alloc] initWithContentsOfFile:plistFile]
I won’t be able to replace the number objects, correct?
So I’m recursing through the data right now and forming a mutable version of the whole thing, and it worked in one instance, but now it’s telling me mutating method sent to immutable object when the whole thing is mutable.

Is there an easier/better way to do this? If it makes a difference, my data is just integers and booleans.

Answer 1

Instead of writing all that custom class junk, you should use NSPropertyListSerialization. Specifically, see the propertyListWithData:options:format:error: method. Example usage:

NSMutableDictionary *d = [NSPropertyListSerialization propertyListWithData:[NSData dataWithContentsOfFile:@"path/to/file"] 
                                                                   options:NSPropertyListMutableContainers
                                                                    format:NULL
                                                                     error:NULL];

This will make all the containers mutable, but keep the leaf nodes (e.g. NSStrings) immutable. There’s also an option to make the leaves mutable too.