Using NSKeyedArchiver to store custom data model

Question

I\'m working on a rss reader. It is just a tableview and each cell shows a custom data model RSSEntry. And I have a NSMutableArray allEntries which contains all RSSEntry I got f

Answer 1

Place all the entries you want to store into an NSArray and use this code:

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:entries];

Where entries is your array of entries. Nice and easy, just one line of code.

To unarchive, just use

NSArray *entries = [NSKeyedUnarchiver unarchiveObjectWithData:data];

NSKeyedArchiver is able to archive any data structure, even a very complex one, of Objective-C objects that implement the NSCoding protocol, including nested NSArrays, NSDictionarys, and custom objects, to a file. NSKeyedUnarchiver does the reverse, taking any data produced by NSKeyedArchiver and reestablishing the original object graph that was archived. Technically, they could just be a single class, but Apple decided to separate them by functionality because this is more grammatically correct or something :)

I assume you are able to write the resulting NSData object to a file, and read it back again.