Question

Is there Hierarchy system in NSMutableData? If so, how do i load information in a hierarchy manner?
Example

//Create path to saving location
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

NSMutableData *gameData;
NSKeyedUnarchiver *decoder;
NSString *documentPath = [documentsDirectory stringByAppendingPathComponent:@"tierSave.dat"];
gameData = [NSData dataWithContentsOfFile:documentPath];
//end

//start loading
    for(NSArray* firstData in gameData){

    decoder = [[NSKeyedUnarchiver alloc] initForReadingWithData:gameData];

    int level1 = [decoder decodeIntegerForKey:level1];
    }
//end

However in for(NSArray* firstData in gameData), the compiler tells me that gameData will not respond to count because it is a NSMutableData instead of NSMutableArray etc, How do i exactly re-implement the code above?

Answer 1

Saving:

• Create a NSArray with your multiple NSData
• Use NSKeyedArchiver to make a NSData from your NSArray

Loading:

• Load a NSData from file
• Use NSKeyedUnarchiver to extract the NSArray
• Loop your NSArray

In code:
NSData *data0 = [NSData data]; // Data 1
NSData *data1 = [NSData data]; // Data 2

/////////// SAVE
// now make a array
NSArray *array = [NSArray arrayWithObjects:data0, data1, nil];

// now archive the data
NSData *archivedData = [NSKeyedArchiver archivedDataWithRootObject:array];
// archivedData contains now a binary plist with your archived array including your NSData objects

[archivedData writeToFile:path atomically:YES];



/////// LOAD
NSData *archivedDataFromFile = [NSData dataWithContentsOfFile:path];

NSArray *newArray = [NSKeyedUnarchiver unarchiveObjectWithData:archivedDataFromFile];

NSData *dataLoaded0 = [newArray objectAtIndex:0];