NSScreencast

Episode source code

Further Reading:

• Archives & Serializations Programming Guide

• Property List Programming Guide

• NSDictionary class reference

• NSCoding Protocol Reference

• NSKeyedArchiver Class Reference

• CocoaDevCentral - Saving Application Data

Property List Serialization

All values must be NSString, NSDate, NSNumber, NSData, NSDictionary, or NSArray. If you try to save an array with NSURL values, it will silently fail.

// writing to a file
NSArray *flavors = [NSArray arrayWithObjects:@"chocolate", @"vanilla", 
                              @"strawberry", nil];

[flavors writeToFile:PATH atomically:YES];


// reading from a file
NSArray *flavorsFromDisk = [NSArray arrayWithContentsOfFile:PATH];

NSKeyedArchiver

// Bookmark.h

@interface Bookmark : NSObject 

@property (nonatomic, copy) NSString *label;
@property (nonatomic, copy) NSString *url;

@end

// Bookmark.m
#import "Bookmark.h"

@implementation Bookmark

@synthesize label = _label;
@synthesize url = _url;

- (id)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    if (self) {
        self.label = [aDecoder decodeObjectForKey:@"label"];
        self.url = [aDecoder decodeObjectForKey:@"url"];
    }
    
    return self;
}

- (void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeObject:self.label forKey:@"label"];
    [aCoder encodeObject:self.url forKey:@"url"];
}

- (void)dealloc {
    [_label release];
    [_url release];
    [super dealloc];
}

@end

// archiving the object
[NSKeyedArchiver archiveRootObject:_bookmarks toFile:_path];

// restoring the object
_bookmarks = [[NSKeyedUnarchiver unarchiveObjectWithFile:_path] retain];