Archiving NSManagedObject with NSCoding
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Archiving NSManagedObject with NSCoding — Hi, I’m Sam
Archiving NSManagedObject with NSCoding — Hi, I’m Sam
Hi, I’m Sam
This is my blog. I also have a website thing.
Archiving NSManagedObject with NSCoding
Posted on February 28, 2010
Several of the apps I have been working on lately have been using Core Data. Core Data is pretty sweet. So far, I really like it.
I needed to persist an array of NSManagedObjects to NSUserDefaults to persist the state of the application between launches. Obviously, I could have done this with another attribute on the Core Data entity, but this approach seemed a lot simpler. I was surprised that NSManagedObject didn't conform to NSCoding. I guess that makes sense because if you store any custom types in your entity, it wouldn't know how to archive them. In my case, (and I would assume most others) I didn't want to archive the entire object since it was already store in Core Data. I just needed to store the object ID.
This was actually really easy. See:
//
// SSManagedObject.h
// Archiving NSManagedObject with NSCoding
//
// Created by Sam Soffes on 2/28/10.
// Copyright 2010 Sam Soffes. All rights reserved.
//
extern NSString *kURIRepresentationKey;
@interface SSManagedObject : NSManagedObject <NSCoding> {
}
@end
//
// SSManagedObject.m
// Archiving NSManagedObject with NSCoding
//
// Created by Sam Soffes on 2/28/10.
// Copyright 2010 Sam Soffes. All rights reserved.
//
#import "SSManagedObject.h"
#import "AppDelegate.h"
NSString *kURIRepresentationKey = @"URIRepresentation";
@implementation SSManagedObject
- (id)initWithCoder:(NSCoder *)decoder {
AppDelegate *appDelegate = [AppDelegate sharedAppDelegate];
NSPersistentStoreCoordinator *psc = [appDelegate persistentStoreCoordinator];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
self = (SSManagedObject *)[[context objectWithID:[psc managedObjectIDForURIRepresentation:(NSURL *)[decoder decodeObjectForKey:kURIRepresentationKey]]] retain];
return self;
}
- (void)encodeWithCoder:(NSCoder *)encoder {
[encoder encodeObject:[[self objectID] URIRepresentation] forKey:kURIRepresentationKey];
}
@end
I always add + (id)sharedAppDelegate to my application delegate to save some typing:
+ (AppDelegate *)sharedAppDelegate {
return (AppDelegate *)[[UIApplication sharedApplication] delegate];
}
Pretty simple right? Then you can do something like this to archive your objects:
[[[AppDelegate sharedAppDelegate] managedObjectContext] save:nil]; NSData *archivedObjects = [NSKeyedArchiver archivedDataWithRootObject:objects]; NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; [userDefaults setObject:archivedObjects forKey:@"someKey"]; [userDefaults synchronize];
Unarchiving is also super easy:
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
NSData *objectsData = [userDefaults objectForKey:@"someKey"];
if ([objectsData length] > 0) {
NSArray *objects = [NSKeyedUnarchiver unarchiveObjectWithData:objectsData]];
}
Hosting Frustrations
Posted on February 21, 2010
Lately I've been struggling with good hosting. Here's three stories about some stuff I've tried. (Skip to the bottom of the post if you just want my conclusion and don't care about the stories.)
I love Heroku. I did a screencast on how awesome they are a few months ago. Since then, I've moved all of my personal apps and all of Tasteful Works's apps to Heroku. They've been really great until recently.
I have two big complains (and one small one) with Heroku.
© 2006-2022 Sam Soffes
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