NSKeyedArchiver或[NSArray writeToFile：atomically：]？

Question

Well I just saved the same data twice and using NSKeyedArchiver the file was about 30KB bigger (from 60KB to 90KB) I know its not much but I'm going to have more of these files and some will be bigger than others. So whats the difference and what are the advantage of using one of the other?

Answer 1

You can stick to -[NSArray writeToFile:atomically:] for simple objects, ie, the ones natively supported by property lists (essentially strings, numbers, dates, byte sequences, as well as arrays and dictionaries).

NSKeyedArchiver would be preferred/necessary over NSArray/NSDictionary if you're storing complex data. As opposed to the property lists created by NSArray or NSDictionary, a keyed archive contains metadata about a whole object graph hierarchy — objects, their identities, their relationships, classes, instance variables, superclasses. Data is keyed, which can be used to maintain forward or backward compatibility by means of ignoring keys (eg instance variables). More information on (keyed) archives is available at the Archives and Serializations Programming Guide .