NSFetchedResultsController requires a non-nil fetchRequest and managedObjectContext - objective-c

i am having a problem since days, i tryed all the solutions here in stackoverflow but anyone gives me a solution.
i am using core data and tableviewcontroller.
My CoreDataTableViewController its correct, i downloaded it from timroadnley and u use it in another projects.
Im getting an error : 'An instance of NSFetchedResultsController requires a non-nil fetchRequest and managedObjectContext'
The application loads correctly but when i press to go to the marksTableviewcontroller, it fails.
THE ERROR IS ON THIS LINE:
- (void)setupFetchedResultsController{
// 1 - Decide what Entity you want
NSString *entityName = #"Marks"; // Put your entity name here
NSLog(#"Setting up a Fetched Results Controller for the Entity named %#", entityName);
// 2 - Request that Entity
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];
// 4 - Sort it if you want
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:#"subject"
ascending:YES
selector:#selector(localizedCaseInsensitiveCompare:)]];
// 5 - Fetch it
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil]; //IN THIS LILE IS THE ERROR, IN "REQUEST"
[self performFetch];
}
THIS IS MY APPDELEGATE:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
marksTVCon.managedObjectContext = self.managedObjectContext;
NSDictionary *defaultsDict = [[NSDictionary alloc] initWithObjectsAndKeys:[NSNumber numberWithBool:YES], #"FirstLaunch", nil];
[[NSUserDefaults standardUserDefaults] registerDefaults:defaultsDict];
NSUserDefaults *sharedDefaults = [NSUserDefaults standardUserDefaults];
if([sharedDefaults boolForKey:#"FirstLaunch"]) {
UIAlertView *message = [[UIAlertView alloc] initWithTitle:#"MYAPP" message:#"Thanks for downloading, hope you love our app" delegate:nil cancelButtonTitle:#"Go app" otherButtonTitles:nil, nil];
[message show];
[sharedDefaults setBool:NO forKey:#"FirstLaunch"];
[sharedDefaults synchronize];
}
return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application
{
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application
{
// Saves changes in the application's managed object context before the application terminates.
[self saveContext];
}
- (void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
#pragma mark - Core Data stack
// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
- (NSManagedObjectContext *)managedObjectContext
{
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
_managedObjectContext = [[NSManagedObjectContext alloc] init];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return _managedObjectContext;
}
// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the application's model.
- (NSManagedObjectModel *)managedObjectModel
{
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"MYAPP" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the application's store added to it.
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"MYAPP.sqlite"];
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
Typical reasons for an error here include:
* The persistent store is not accessible;
* The schema for the persistent store is incompatible with current managed object model.
Check the error message to determine what the actual problem was.
If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.
If you encounter schema incompatibility errors during development, you can reduce their frequency by:
* Simply deleting the existing store:
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil]
* Performing automatic lightweight migration by passing the following dictionary as the options parameter:
#{NSMigratePersistentStoresAutomaticallyOption:#YES, NSInferMappingModelAutomaticallyOption:#YES}
Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
#pragma mark - Application's Documents directory
// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
#end
If you need to ask for anyother peace of code pliz ask for it, I think the problem is in there, but im not pretty Sure.

Related

CoreData NSManagedObjectContext not found

New to iOS development. I am trying to use the core data stack in a sample app, which fetches data over network and simply updates the UI. Whilst creating the project, the "Use Core Data" checkbox was ticked which generates bunch of boilerplate code. However, on XCode 8.2.1, the I only see the NSPersistentContainer implementation within the AppDelegate.m file.
- (NSPersistentContainer *)persistentContainer {
// The persistent container for the application. This implementation creates and returns a container, having loaded the store for the application to it.
#synchronized (self) {
if (_persistentContainer == nil) {
_persistentContainer = [[NSPersistentContainer alloc] initWithName:#"ergast_coredata_objc"];
[_persistentContainer loadPersistentStoresWithCompletionHandler:^(NSPersistentStoreDescription *storeDescription, NSError *error) {
if (error != nil) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
NSLog(#"Unresolved error %#, %#", error, error.userInfo);
abort();
}
}];
}
}
return _persistentContainer;
}
There is no boilerplate code for the NSManagedObjectContext as most of the tutorials would have you believe.
Hence, the following block within the ViewController.m class fails with a Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[AppDelegate managedObjectContext]: unrecognized selector sent to instance
-(NSArray *)getSeasonsList{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"SeasonData"];
NSError *error = nil;
NSArray *results = [[self getManagedObjectContext] executeFetchRequest:request error:&error];
if (!results) {
NSLog(#"Error fetching objects: %#\n%#", [error localizedDescription], [error userInfo]);
abort();
}
return results;
}
- (NSManagedObjectContext *)getManagedObjectContext {
NSManagedObjectContext *context = nil;
id delegate = [[UIApplication sharedApplication] delegate];
context = [delegate managedObjectContext];
return context;
}
Tried looking online but most of the tutorials are Swift based it seems. What am i missing here? Is the developer supposed to provide the implementation for the NSManagedObjectContext? Would be much appreciated if someone can provide with an Objective-c based sample code.
Thanks!
See in saveContext method
pragma mark - Core Data Saving support
- (void)saveContext {
// OBSERVE HERE
NSManagedObjectContext *context = self.persistentContainer.viewContext;
NSError *error = nil;
if ([context hasChanges] && ![context save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, error.userInfo);
abort();
}
}
Whenever you need NSManagedObjectContext instance, access like this
NSManagedObjectContext *context = self.persistentContainer.viewContext;
self.persistentContainer OR classObject.persistentContainer
Modify the "getManagedObjectContext" method as below
- (NSManagedObjectContext *)getManagedObjectContext {
AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [[delegate persistentContainer] viewContext];
return context;
}
I didn't tested this, but hope this will work
I have a category for appdelegate that was included in one of the old Stanford CS193P that uses objective-c. Some of it might be deprecated, though. Also check out https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/CoreData/InitializingtheCoreDataStack.html#//apple_ref/doc/uid/TP40001075-CH4-SW1 has objective-c sample. Post back if that helps.
//
// PhotomaniaAppDelegate+MOC.m
// Photomania
//
// This code comes from the Xcode template for Master-Detail application.
#import "PhotomaniaAppDelegate+MOC.h"
#import <CoreData/CoreData.h>
#implementation PhotomaniaAppDelegate (MOC)
#pragma mark - Core Data
- (void)saveContext:(NSManagedObjectContext *)managedObjectContext
{
NSError *error = nil;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
- (NSManagedObjectContext *)createMainQueueManagedObjectContext
{
NSManagedObjectContext *managedObjectContext = nil;
NSPersistentStoreCoordinator *coordinator = [self createPersistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return managedObjectContext;
}
// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the application's model.
- (NSManagedObjectModel *)createManagedObjectModel
{
NSManagedObjectModel *managedObjectModel = nil;
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"Photomania" withExtension:#"momd"];
managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return managedObjectModel;
}
// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the application's store added to it.
- (NSPersistentStoreCoordinator *)createPersistentStoreCoordinator
{
NSPersistentStoreCoordinator *persistentStoreCoordinator = nil;
NSManagedObjectModel *managedObjectModel = [self createManagedObjectModel];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"MOC.sqlite"];
NSError *error = nil;
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:managedObjectModel];
if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
Typical reasons for an error here include:
* The persistent store is not accessible;
* The schema for the persistent store is incompatible with current managed object model.
Check the error message to determine what the actual problem was.
If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.
If you encounter schema incompatibility errors during development, you can reduce their frequency by:
* Simply deleting the existing store:
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil]
* Performing automatic lightweight migration by passing the following dictionary as the options parameter:
#{NSMigratePersistentStoresAutomaticallyOption:#YES, NSInferMappingModelAutomaticallyOption:#YES}
Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return persistentStoreCoordinator;
}
// Returns the URL to the application's Documents directory
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
#end
Also, check out this project https://github.com/m2mtech/photomania-2013-14/tree/master/Photomania/CoreDataTableViewController/MOC More info how Core Data was used with this implementation.

NSFetchedResultController won't show data in IOS 5

I am new to IOS development. At the moment I'm building an iPad app, what gets data back from the webservice, saves it in a core database and shows it in a tableview using NSFetchedResultController.
What is the problem. In IOS6 it al works like a charm, in IOS 5.0 it saves the data but not showing it in the tableview. It gives the following error.
CoreData: error: Serious application error. An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. The NIB data is invalid. with userInfo (null)
And when I test in IOS 5.1 it does not do anything. It does not shows data in a tableview and data is not being stored in core database.
Here is what I do. In my view did appear I check if there is a document I can use.
if (!self.genkDatabase) { // we'll create a default database if none is set
NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
url = [url URLByAppendingPathComponent:#"Default appGenk Database"];
self.genkDatabase = [[UIManagedDocument alloc] initWithFileURL:url]; // setter will create this for us on disk
}
Then it goes to my setter. And next in usedocument gonna check in which state my document is.
- (void)setGenkDatabase:(UIManagedDocument *)genkDatabase
{
if (_genkDatabase != genkDatabase) {
_genkDatabase = genkDatabase;
[self useDocument];
}
NSLog(#"Comes in the setdatabase methode.");
}
- (void)useDocument
{
NSLog(#"Comses in the use document");
if (![[NSFileManager defaultManager] fileExistsAtPath:[self.genkDatabase.fileURL path]]) {
// does not exist on disk, so create it
[self.genkDatabase saveToURL:self.genkDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
NSLog(#"create");
[self setupFetchedResultsController];
NSLog(#"create 2");
[self fetchNewsIntoDocument:self.genkDatabase];
NSLog(#"create 3");
}];
} else if (self.genkDatabase.documentState == UIDocumentStateClosed) {
NSLog(#"closed news");
// exists on disk, but we need to open it
[self.genkDatabase openWithCompletionHandler:^(BOOL success) {
[self setupFetchedResultsController];
}];
} else if (self.genkDatabase.documentState == UIDocumentStateNormal) {
NSLog(#"normal");
// already open and ready to use
[self setupFetchedResultsController];
}
}
Finally I fetch my data in my document using the following function.
- (void)fetchNewsIntoDocument:(UIManagedDocument *)document
{
dispatch_queue_t fetchNews = dispatch_queue_create("news fetcher", NULL);
dispatch_async(fetchNews, ^{
NSArray *news = [GenkData getNews];
[document.managedObjectContext performBlock:^{
int newsId = 0;
for (NSDictionary *genkInfo in news) {
newsId++;
[News newsWithGenkInfo:genkInfo inManagedObjectContext:document.managedObjectContext withNewsId:newsId];
NSLog(#"news inserted");
}
[document saveToURL:document.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:NULL];
}];
});
dispatch_release(fetchNews);
}
For the problem in IOS 5.0 is this my NSFetchResultController method.
- (void)setupFetchedResultsController // attaches an NSFetchRequest to this UITableViewController
{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"News"];
request.sortDescriptors = [NSArray arrayWithObjects:[NSSortDescriptor sortDescriptorWithKey:#"date" ascending:YES],nil];
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.genkDatabase.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
}
I am doing this like the example from Paul Hegarty in stanford university. You can find the example Photomania over here.
Hope anyone can help me!
Kind regards

Core Data without Master Detail Template

I want to create an iphone application which uses Core Data.
As i understood, only master-detail application template gives me an option to use Core Data. But it creates table view.
What i want to use is view controller not table view controller.
I couldnt use core data with single view application template..
Which way should I follow to overcome this issue?
Thanks.
You should realize that CoreData is a framework that is not bound to any UIKit components like UITableView. You can freely use it in any sort of an application. All you have to do is to create your singleton class that manages CoreData operations and add CoreData.framework to your project.
Here is my DataAccessLayer template:
DataAccessLayer.h
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#interface DataAccessLayer : NSObject
#property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (strong, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (strong, nonatomic) NSPersistentStoreCoordinator *storeCoordinator;
+ (DataAccessLayer *)sharedInstance;
- (void)saveContext;
#end
DataAccessLayer.m
#import "DataAccessLayer.h"
#interface DataAccessLayer ()
- (NSURL *)applicationDocumentsDirectory;
#end
#implementation DataAccessLayer
#synthesize storeCoordinator;
#synthesize managedObjectModel;
#synthesize managedObjectContext;
+ (DataAccessLayer *)sharedInstance {
__strong static DataAccessLayer *sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[DataAccessLayer alloc] init];
sharedInstance.storeCoordinator = [sharedInstance persistentStoreCoordinator];
sharedInstance.managedObjectContext = [sharedInstance managedObjectContext];
});
return sharedInstance;
}
#pragma mark - Core Data
- (void)saveContext {
#synchronized(self) {
NSError *error = nil;
if (managedObjectContext != nil)
{
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error])
{
NSLog(#"error: %#", error.userInfo);
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Oops!"
message:#"Something has gone terribly wrong! You need to reinstall the app in order for it to work properly."
delegate:nil
cancelButtonTitle:#"Close."
otherButtonTitles:nil, nil];
[alert show];
}
}
}
}
#pragma mark Core Data stack
/**
Returns the managed object context for the application.
If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
*/
- (NSManagedObjectContext *)managedObjectContext {
if (managedObjectContext != nil)
{
return managedObjectContext;
}
if (storeCoordinator != nil)
{
managedObjectContext = [[NSManagedObjectContext alloc] init];
[managedObjectContext setPersistentStoreCoordinator:storeCoordinator];
}
return managedObjectContext;
}
/**
Returns the managed object model for the application.
If the model doesn't already exist, it is created from the application's model.
*/
- (NSManagedObjectModel *)managedObjectModel {
if (managedObjectModel != nil)
{
return managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"DataModel" withExtension:#"momd"];
managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return managedObjectModel;
}
/**
Returns the persistent store coordinator for the application.
If the coordinator doesn't already exist, it is created and the application's store added to it.
*/
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
if (storeCoordinator != nil)
{
return storeCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"words_db.sqlite"];
NSError *error = nil;
storeCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![storeCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error])
{
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
Typical reasons for an error here include:
* The persistent store is not accessible;
* The schema for the persistent store is incompatible with current managed object model.
Check the error message to determine what the actual problem was.
If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.
If you encounter schema incompatibility errors during development, you can reduce their frequency by:
* Simply deleting the existing store:
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil]
* Performing automatic lightweight migration by passing the following dictionary as the options parameter:
[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Oops!"
message:#"Something has gone terribly wrong! You need to reinstall the app in order for it to work properly."
delegate:nil
cancelButtonTitle:#"Close."
otherButtonTitles:nil, nil];
[alert show];
}
return storeCoordinator;
}
#pragma mark Application's Documents directory
/**
Returns the URL to the application's Documents directory.
*/
- (NSURL *)applicationDocumentsDirectory {
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
#end
You will also have to create an .xcdatamodeld file in order to create your Data Model objects. And replace the name here with appropriate
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"DataModel" withExtension:#"momd"];

How to remove a core data persistent store

I need to delete my persistent store (doing it object by object is not practical because I have over 100,000 objects). I've tried this:
- (IBAction)resetDatabase:(id)sender {
NSPersistentStore* store = [[__persistentStoreCoordinator persistentStores] lastObject];
NSError *error = nil;
NSURL *storeURL = store.URL;
// release context and model
[__managedObjectContext release];
[__managedObjectModel release];
__managedObjectModel = nil;
__managedObjectContext = nil;
[__persistentStoreCoordinator removePersistentStore:store error:nil];
[__persistentStoreCoordinator release];
__persistentStoreCoordinator = nil;
[[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:&error];
if (error) {
NSLog(#"filemanager error %#", error);
}
// recreate the stack
__managedObjectContext = [self managedObjectContext];
}
But I get this error when I try to insert entities into the store afterwards:
This NSPersistentStoreCoordinator has no persistent stores. It cannot perform a save operation.
Update:
I tried releasing the MOC and MOM before removing the persistent store but I still get the same error.
Here is how I do a "reset data" function in several apps:
- (void)reset {
// Release CoreData chain
[_managedObjectContext release];
_managedObjectContext = nil;
[_managedObjectModel release];
_managedObjectModel = nil;
[_persistentStoreCoordinator release];
_persistentStoreCoordinator = nil;
// Delete the sqlite file
NSError *error = nil;
if ([fileManager fileExistsAtPath:_storeURL.path])
[fileManager removeItemAtURL:_storeURL error:&error];
// handle error...
}
Basically I just release the CoreData chain, then delete the persistentStore file. That's what you are trying to do, without using removePersistentStore, which I do not care since I will just rebuild the persistentStore coordinator later. Then at next core data call the chain is rebuilt transparently using singleton-lazy-style constructors like :
- (NSManagedObjectModel *) managedObjectModel {
if (!_managedObjectModel)
_managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];
return _managedObjectModel;
}
You can do it externally given that you only need to do this while developing your application. I have a terminal open in which I remove the store manually before re-running my app. All you need to know is where it is located. I log it to console everytime my app runs with the following code:
[[CoreDataSingleton sharedManager] managedObjectContext]; //be sure to create the store first!
//Find targeted mom file in the Resources directory
NSString *momPath = [[NSBundle mainBundle] pathForResource:#"Parking" ofType:#"mom"];
NSLog(#"momd path: %#",momPath);
Hope that helps!
You need to make sure that any managed object context attached to the persistent store have been released before you try to delete the store. Otherwise, the context will evoke that error.

Testing controller method with OCMock and Core Data

I am just grasping the concepts of TDD and mocking, and am running into an issue in terms of how to properly. I have a sheet that drops down and lets a user create a new core data object and save it to the data store. I am not sure if I am taking the best approach to testing it.
- (IBAction)add:(id)sender
{
NSString *itemName = [self.itemNameTextField stringValue];
SGItem *newItem = [NSEntityDescription insertNewObjectForEntityForName:kItemEntityName inManagedObjectContext:[self managedObjectContext]];
newItem.name = itemName;
NSError *error = nil;
BOOL canSaveNewItem = [[self managedObjectContext] save:&error];
if (!canSaveNewItem)
{
[NSApp presentError:error];
}
[self clearFormFields]; // Private method that clears text fields, disables buttons
[NSApp endSheet:[self window] returnCode:NSOKButton];
}
I'm trying to write two test methods to test this: one that tests the scenario where the managed object can't save and one where it successfully saves.
#interface SGAddItemWindowControllerTests : SGTestCase
{
#private
SGAddItemWindowController *addItemWindowController;
id mockApp;
id mockNameField;
}
- (void)setUp
{
mockNameField = [OCMockObject mockForClass:[NSTextField class]];
mockApp = [OCMockObject mockForClass:[NSApplication class]];
addItemWindowController = [[BLAddItemWindowController alloc] init];
[addItemWindowController setValue:mockNameField forKey:#"itemNameTextField"];
}
- (void)testAddingNewItemFromSheetFailed
{
// Setup
NSString *fakeName = #"";
[[[mockNameField expect] andReturn:fakeName] stringValue];
[[mockApp expect] presentError:[OCMArg any]];
// Execute
[addItemWindowController add:nil];
// Verify
[mockApp verify];
}
- (void)testAddingNewItemFromSheetSucceeds
{
// Setup
NSString *fakeName = #"Item Name";
[[[mockNameField expect] andReturn:fakeName] stringValue];
[[mockApp expect] endSheet:[OCMArg any] returnCode:NSOKButton];
// Execute
[addItemWindowController add:nil];
// Verify
[mockApp verify];
[mockNameField verify];
}
#end
Here are the issues I know I have, but am not sure how to work out:
I am not sure how to handle dealing with the managed object context in terms of the test. Should I bring up the entire core data stack or just create a mock of NSManagedObjectContext?
The idea of just setting the text field values as the way to trigger the if statement seems wrong. Ideally I think I should stub out the save: method and return YES or NO, but given question 1 I'm not sure about the Core Data aspects of it all.
I think I'm on the right track, but I could use a second opinion on how to tackle my issues and set me on the right path for testing the code snippet.
Justin,
What I do for question #1 is to create an actual NSManagedObjectContext but create an im-memory persistence store. Nothing hits the disk and I test the CoreData version of the truth.
I have a MWCoreDataTest class (extends in my case GTMTestCase) that builds the moc and initializes the persistence store
- (NSManagedObjectContext *) managedObjectContext {
if (managedObjectContext != nil) {
return managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext = [[NSManagedObjectContext alloc] init];
[managedObjectContext setPersistentStoreCoordinator: coordinator];
}
return managedObjectContext;
}
- (NSPersistentStoreCoordinator*)persistentStoreCoordinator;
{
if (persistentStoreCoordinator) return persistentStoreCoordinator;
NSError* error = nil;
NSManagedObjectModel *mom = [self managedObjectModel];
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc]
initWithManagedObjectModel:mom];
if (![persistentStoreCoordinator addPersistentStoreWithType:NSInMemoryStoreType
configuration:nil
URL:nil
options:nil
error:&error]) {
[[NSApplication sharedApplication] presentError:error];
return nil;
}
return persistentStoreCoordinator;
}
WRT #2, I think that's ok - if you plan on testing more than one behavior in the class, move the
[addItemWindowController setValue:mockNameField forKey:#"itemNameTextField"];
to the testAdding.. method
If you solve #1, then you could just set the itemNameText field to nil and your save validation would trigger.
WRT #3, I would validate that building a mock on NSApp === building a mock on NSApplication
What is that you want to test? Do you want to test that Core Data does the saving or not? Or, do you want to test that your application responds correctly to the result of the call to CoreData?
Either way I think you should extract a method that performs the saving along the lines of:
-(BOOL)saveNewItem:(NSString *)itemName error:(NSError **)error {
SGItem *newItem = [NSEntityDescription insertNewObjectForEntityForName:kItemEntityName inManagedObjectContext:[self managedObjectContext]];
newItem.name = itemName;
NSError *error = nil;
return[[self managedObjectContext] save:&error];
}
- (IBAction)add:(id)sender {
NSString *itemName = [self.itemNameTextField stringValue];
NSError *error = nil;
BOOL canSaveNewItem = [self saveNewItem:itemName error:&error];
if (!canSaveNewItem) {
[NSApp presentError:error];
}
[self clearFormFields]; // Private method that clears text fields, disables buttons
[NSApp endSheet:[self window] returnCode:NSOKButton];
}
This way you can test that Core Data saving works as expected by settings up an in memory store and not have to care about the business logic. You should also be able to override or mock the result of this method for testing the business logic.
I would perhaps even move all the Core Data stuff to a separate class that would encapsulate the interaction for easier mocking.