Question

I have an iPhone application that pulls some JSON data from a server and then parses it into an array of dictionaries which contains sub-arrays and sub-dictionaries.

Right now I have this stored in an ivar timeTablethen copying it to filteredTimetable before looping through filteredTimetable and removing the objects I don’t need.

The problem I am having is when I try restore the array so it can be filtered again. The objects that have been removed previous from the copied NSArray are removed from the original NSArray too.

filteredTimeTable = [[NSMutableArray alloc] initWithArray:timeTable copyItems:YES];

I assume this is because filteredTimeTable is simply storing a pointers to the objects in timeTable rather than copying the memory.

Here is an example of my data structure:

    [
        {"time":"09:00",
        "events": [
            { "module":"COMP319", "type":"lecture", "room":"BROD-108:80" }
            { "module":"COMP320", "type":"lab", "room":"BROD-LT" }
        ]},

When I remove a module that is no longer required I can’t restore the element.

So is there anyway to do a full copy including all the sub-objects?

Answer 1

You could just keep the original JSON string around and re-parse it.

If you don’t want to do that for some reason, and if it’s all valid property list objects (NSArray, NSDictionary, NSString, NSNumber, NSDate, NSData), the simplest approach is to use property list serialization:

NSData *archive = [NSPropertyListSerialization dataWithPropertyList:originalObject format:NSPropertyListBinaryFormat_v1_0 options:0 error:NULL];
NSMutableArray *copiedObject = [NSPropertyListSerialization propertyListWithData:archive options:NSPropertyListMutableContainers format:NULL error:NULL];