i have 2 entities Called Playlists and Songs. First i'm passing the selected playlist into my singleton by using this code:
optionsSingle = [rowNumber singleObj];
optionsSingle.selectedRowNow = [devices objectAtIndex:indexPath.row];
the optionsSingle.selectedRowNow will return something like this, depending on name:
0xb922600 <x-coredata://053340C7-00A3-47EA-A213-4A9B6164504F/Playlists/p6> ; data: {
playlistName = playlist1;
songs = "<relationship fault: 0xb961480 'songs'>";
})
The problem is when i try to use this playlist object in the addSongsViewController it do not seem to work.
Im trying to include something like this to the songsDone method, but it wont let me use the addSongsObject. I've included the 2 entities to the .m file. The optionsSingle.selectedRowNumber is declared as as ´playlist´object type. How come i cant use this method on my playlist object that has been passed?
[optionsSingle.selectedRowNumber addSongsObject:newManagedObject2]
songsDone Method.
-(IBAction)songsDone:(id)sender{
AppDelegate *appDelegate =
[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context =
[appDelegate managedObjectContext];
Songs *newManagedObject2 = (Songs*)[NSEntityDescription insertNewObjectForEntityForName:#"Songs" inManagedObjectContext:context];
NSDate *today= [NSDate date];
[newManagedObject2 setValue:video.author forKey:#"author"];
[newManagedObject2 setValue:video.videoid forKey:#"link"];
[newManagedObject2 setValue:video.title forKey:#"songName"];
[newManagedObject2 setValue:today forKey:#"created"];
NSError *error = nil;
if (![_managedObjectContext save:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
(From my above comment:) If selectedRowNumber contains a Playlists object then you should declare it as such, and not as NSObject. Otherwise the compiler cannot "know" that it responds to addSongsObject:. - I.e. you should replace NSObject by Playlists in the definition of the selectedRowNumber property.
Related
I'm using a data model called settings which I setup in didLoad of my viewController:
settings = [NSEntityDescription insertNewObjectForEntityForName:#"Settings" inManagedObjectContext:[self managedObjectContext]];
Heres the managedobjectContext method:
- (NSManagedObjectContext *)managedObjectContext {
NSManagedObjectContext *context = nil;
id delegate = [[UIApplication sharedApplication] delegate];
if ([delegate performSelector:#selector(managedObjectContext)]) {
context = [delegate managedObjectContext];
}
return context;
}
When my stepper increments I want to update a string and then update the db.
- (IBAction)RowStepperAction:(UIStepper *)sender
{
double value = [sender value];
settings.numberofrows = [NSNumber numberWithDouble:value];
[self.RowNumber setText:[NSString stringWithFormat:#"%d", (int)value]];
NSError *error = nil;
// Save the object to persistent store
if (![[self managedObjectContext] save:&error]) {
NSLog(#"Can't Save! %# %#", error, [error localizedDescription]);
}
}
When I come to load the view again I do:
[self.ColumnStepper setValue:[settings.numberofcolumns doubleValue]];
[self.RowStepper setValue:[settings.numberofrows doubleValue]];
This returns the default values I set in the database. Why is this?
Every time you load the view again, you're creating a brand new settings object :
settings = [NSEntityDescription insertNewObjectForEntityForName:#"Settings" inManagedObjectContext:[self managedObjectContext]];
This will have your default values. You need instead to fetch your existing settings object, and only create a new one if that doesn't exist.
Your database will currently have several settings objects, one for each time you've loaded the view.
I have a method which allows the user to export a .csv file of all data in my Core Data model. I'm using the wonderful CHCSV Parser after performing a fetchRequest to fetch the stored results. Once the .csv has been created, it gets attached to an email and exported from the device. This all works fine, the issues come when I delete the data.
I am using a somewhat popular technique to delete my data (by popular I mean it has been recommended on lots of Stack Overflow answers I have came researched). I simply fetch all objects and delete them one by one.
// Create fetchRequest
NGLSAppDelegate *appDelegate = (NGLSAppDelegate *)[[UIApplication sharedApplication]delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"NGLS"
inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSError *error;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
// Delete objects
for (Model *results in fetchedObjects) {
[context deleteObject:(id)results];
NSLog(#"NGLS objects deleted");
};
My model is simple and only has two entities, so I use the same code for the other Admin entity too. This is all fine, all objects are deleted, and I can confirm this by doing another fetchRequest which returns the object count for each entity - both have a count of zero. The problem occurs when I try to save data back to either entity after the delete has been executed.
The ViewController with the above code is an "Admin" control screen, where the user can login and also export the data. So when the user logs in, here is the code to save:
// Save login details
[_managedObjectAdmin setValue:user forKey:#"userLogin"];
[_managedObjectAdmin setValue:site forKey:#"siteLocation"];
NSError *error;
[[self.managedObjectAdmin managedObjectContext] save:&error];
I then perform the fetchRequest above and export all data when the "Export" button is pressed. After that is complete, when I try to login on the same ViewController, the output is:
2014-10-27 12:43:49.653 NGLS[19471:607] <NSManagedObject: 0x7a8c2460> (entity: Admin; id: 0x7a82e3e0 <x-coredata://3C9F3807-E314-439C-8B73-3D4459F85156/Admin/p30> ; data: <fault>)
If I navigate back to another ViewController (using my navigation controller), then go back to the "Admin" control screen and try to login again, I get this output:
2014-10-27 12:44:04.530 NGLS[19471:607] *** Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0x7a82e3e0 <x-coredata://3C9F3807-E314-439C-8B73-3D4459F85156/Admin/p30>''
(I can post the full log if requested).
I have tried many things in an attempt to resolve this issue. Core Data is complex and I dont quite understand what I need to do to fix this. I have tried to delete the persistentStore and create it again, and the same with the managedObjectContext but nothing I have tried has worked. I implemented a resetStore method in my AppDelegate to delete and rebuild the store as follows:
- (void)resetStores {
NSError *error;
NSURL *storeURL = [[_managedObjectContext persistentStoreCoordinator] URLForPersistentStore:[[[_managedObjectContext persistentStoreCoordinator] persistentStores] lastObject]];
// lock the current context
[_managedObjectContext lock];
[_managedObjectContext reset];//to drop pending changes
//delete the store from the current managedObjectContext
if ([[_managedObjectContext persistentStoreCoordinator] removePersistentStore:[[[_managedObjectContext persistentStoreCoordinator] persistentStores] lastObject] error:&error])
{
// remove the file containing the data
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:&error];
//recreate the store like in the appDelegate method
[[_managedObjectContext persistentStoreCoordinator] addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error];//recreates the persistent store
}
[_managedObjectContext unlock];
}
And also tried this method:
- (NSPersistentStoreCoordinator *)resetPersistentStore
{
NSError *error = nil;
if ([_persistentStoreCoordinator persistentStores] == nil)
return [self persistentStoreCoordinator];
_managedObjectContext = nil;
NSPersistentStore *store = [[_persistentStoreCoordinator persistentStores] lastObject];
if (![_persistentStoreCoordinator removePersistentStore:store error:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
// Delete file
if ([[NSFileManager defaultManager] fileExistsAtPath:store.URL.path]) {
if (![[NSFileManager defaultManager] removeItemAtPath:store.URL.path error:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
// Delete the reference to non-existing store
_persistentStoreCoordinator = nil;
NSPersistentStoreCoordinator *r = [self persistentStoreCoordinator];
return r;
}
But neither of these work. What I have found to work is after the export has completed, by closing and reopening the app everything works as normal again. I have tried to figure out what process occurs when closing/opening the app in regards to Core Data but I just don't know what to look for. I have researched many questions on Stack Overflow and tried all the solutions but nothing works for me. I really need some help on this, or else I'm going to have to force the user to quit the app after the export is done by a exit(0); command (because it's not getting submitted to the App Store, its for in-house employees) although I don't want that solution, surely there is a way I can just reset my database and continue to use the app without having to shut it down every time. Thanks in advance.
References:
Deleting all records from Core Data
Reset a Core Data persistent store
How do I delete all objects from my persistent store in Core Data
I have managed to solve the issue by simply refreshing the view. By calling my viewDidLoad method after the export is complete I create a new managedObject ready to use as normal, without leaving that ViewController or exiting the app altogether.
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib
// Create fetchRequest
NGLSAppDelegate *appDelegate = (NGLSAppDelegate *)[[UIApplication sharedApplication]delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Admin" inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
// Fetch last object
Model *admin = [fetchedObjects lastObject];
// Populate login fields with last stored details
if (admin.userLogin == nil) {
//NSLog(#"Login empty");
} else {
self.usernameField.text = admin.userLogin;
self.siteLocationField.text = admin.siteLocation;
}
// Create new managed object using the Admin entity description
NSManagedObject *ManagedObjectAdmin;
ManagedObjectAdmin = [NSEntityDescription insertNewObjectForEntityForName:#"Admin"
inManagedObjectContext:context];
// Declare managed object
self.managedObjectAdmin = ManagedObjectAdmin;
// Save context
NSError *saveError = nil;
[context save:&saveError];
// ... more stuff
}
The solution was so simple all along. I will leave this question/answer up so other people can benefit from it if they find themselves in my situation. Thanks.
EDIT: Re-creating the managedObjectAdmin anywhere after the export works too, there is no specific need to call the viewDidLoad method. After the export has completed, I can simply create the new managedObject and save the context and continue using the app as normal, without having to navigate to another ViewController first or restarting the app.
In my app I have 2 detail view controllers:
product name update controller
product properties update controller
In product properties update view controller everything is fine there is nothing wrong.
In product name update view controller however saving the context does not give any error. I see that the product name change in root view controller but when I re-open my app the product name shows me the old name. So it is not persisted.
What is my problem according to my updateProduct method:
-(void)updateProduct:(id)sender
{
AppDelegate *delegate = [UIApplication sharedApplication].delegate;
NSManagedObjectContext *context = [delegate managedObjectContext];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:#"Products" inManagedObjectContext:context]];
NSError *error = nil;
NSPredicate *predicateID =[NSPredicate predicateWithFormat:#"productID==%d",[secim intValue]];
[request setPredicate:predicateID];
NSArray *myobj=[context executeFetchRequest:request error:&error];
NSManagedObject *prod1=[myobj objectAtIndex:0];
[prod1 setValue:textProduct1.text forKey:#"productName"];
if (![context save:&error]) {
NSLog(#"Can't Save! %# %#", error, [error localizedDescription]);
}
[self.navigationController popToRootViewControllerAnimated:YES];
NSLog(#"Data saved");
}
In addition to #Mundi here you are doing the following
NSArray *myobj = [context executeFetchRequest:request error:&error];
NSManagedObject *prod1 = [myobj objectAtIndex:0];
but you are not checking against error and neither if myobj contains elements.
ALWAYS check for errors whereas there is the possibility to have them.
Check with a breakpoint if your updateProduct method is called. I suspect it is not.
In the light of the other discussion, make sure that
the managed object context is not nil
prod1 (the managed object) is not nil
You can do this with breakpoints in the debugger or with log statements.
So I have a utility app and I am trying to save some text into a "To" and "Message: text field on the Flipside View Controller. However, my data won't save. I am new to objective C and I have been using multiple different tutorials to the point where I have totally confused myself. Hopefully you can help me out. Not sure what else to do at this point...
FlipsideViewController.m
#import "CCCFlipsideViewController.h"
#import "CCCAppDelegate.h"
#import "CCCMainViewController.h"
#import "MessageDetails.h"
#interface CCCFlipsideViewController ()
{
// NSManagedObjectContext *context;
}
#end
#implementation CCCFlipsideViewController
#synthesize allMessageDetails;
#synthesize managedObjectContext;
- (void)awakeFromNib
{
[super awakeFromNib];
CCCAppDelegate *appDelegateController = [[CCCAppDelegate alloc]init];
self.managedObjectContext = appDelegateController.managedObjectContext;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"MessageDetails" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSError *error;
self.allMessageDetails = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
/*
NSManagedObject *managedObject; = [_fetchedResultsController valueForKey:#"to"];
self.toTextField.text = managedObject to;
messageDetails.to = [allMessageDetails firstObject];
self.toTextField.text = messageDetails.to;
messageDetails.message = [allMessageDetails valueForKey:#"message"];
self.messageTextField.text = messageDetails.message;
*/
NSLog(#"The 'to' is currently at %# after viewdidload", self.toTextField.text);
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
return [textField resignFirstResponder]; //function says that if (bool) the text field is open and the keyboard hits return, text field is to resign first responder.
}
#pragma mark - Actions
- (IBAction)done:(id)sender
{
[self.delegate flipsideViewControllerDidFinish:self];
}
- (IBAction)resignFirstResponder:(id)sender {
[self.toTextField resignFirstResponder];
[self.messageTextField resignFirstResponder];
NSLog(#"Resigned First Responder");
}
- (IBAction)save:(id)sender {
// Create a new instance of the entity managed by the fetched results controller.
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
// If appropriate, configure the new managed object.
[newManagedObject setValue:self.toTextField.text forKey:#"to"];
[newManagedObject setValue:self.messageTextField.text forKey:#"message"];
// Save the context.
NSError *error = nil;
if (![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. 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]);
abort();
}
}
#pragma mark -
#pragma mark Fetched results controller
- (NSFetchedResultsController *)fetchedResultsController {
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
/*
Set up the fetched results controller.
*/
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"MessageDetails" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"to" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:#"Root"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
NSError *error = nil;
if (![_fetchedResultsController performFetch:&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.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _fetchedResultsController;
}
#end
I didn't look at all your code because there was a problem near the top that negates everything you do thereafter. Don't alloc/init your app delegate in awakeFromNib or anywhere else for that matter. The one and only instance of your app delegate already exists (I have no idea what happens when there is more than one app delegate).
CCCFlipsideViewController needs to gain access to the managed object context through another means. Perhaps CCCMainViewController (or another view controller) could set the CCCFlipsideViewController's managedObjectContext property. If CCCMainViewController does not have access to the managed object context, have the app delegate pass that context to it.
Example:
App delegate sets a managedObjectContext property on the root view controller; the root view controller, in turn, sets the managedObjectContext property on a child view controller (like your flipside VC), etc.
You don't seem to ever actually set self.messageTextField.text or self.toTextField.text to anything -- you have commented out code in your viewDidLoad method which sets these fields. bilobatum is entirely correct about your AppDelegate issue as well -- you could also use something like
[((NSObject*)[UIApplication sharedApplication].delegate) valueForKey: #"managedObjectContext"];
to get the app delegate for your application if you want to fix that fast, though long term bilobatum's solution to this is better design.
Honestly, I think you've done quite a number on this code... ;)
OK, first off, in your save method, don't create another NSManagedObjectContext, use the instance variable you already declared, "managedObjectContext."
Secondly, I think you've made things way too complicated for yourself... Storing Core Data is actually shockingly simple once you've created the NSManagedObject subclasses and set up everything in the App Delegate...
It seems as if you wouldn't need any info from the "fetchedResultsController" at that point in your code, since you're saving, not fetching. Maybe try changing your save method to something like:
- (IBAction)save:(id)sender {
NSEntityDescription *entity = [NSEntityDescription insertNewObjectForEntityForName:#"MessageDetails" inManagedObjectContext:self.managedObjectContext];
// If appropriate, configure the new managed object.
[entity setValue:self.toTextField.text forKey:#"to"];
[entity setValue:self.messageTextField.text forKey:#"message"];
// Save the context.
NSError *error = nil;
[self.managedObjectContext save:&error]
if (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.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
Edit: And to get the managed object context from the app delegate...
Right after your #synthesize's, create a variable for the App Delegate.
AppDelegate* appDelegateController;
And in viewDidLoad, initialize it:
appDelegateController = (AppDelegate*)[[UIApplication sharedApplication] delegate];
Right after viewDidLoad (or anywhere you want), you can stick in a method to declare the managed object context:
- (NSManagedObjectContext*)managedObjectContext {
return appDelegateController.managedObjectContext;
}
Then back in viewDidLoad, call that method with:
self.managedObjectContext = [self managedObjectContext];
I use a singleton for working with arrays etc. cross the views in the application.
To initialize the singleton and the NSManagedObjectContext, so that I can fetch objects, I use:
+(DataControllerSingleton *)singleDataController
{
static DataControllerSingleton * single=nil;
#synchronized(self)
{
if(!single)
{
single = [[DataControllerSingleton alloc] init];
NSManagedObjectContext *context = [single.fetchedResultsController managedObjectContext];
single.masterCareList = [[NSMutableArray alloc] init];
}
}
return single;
}
When I insert a new object that object will not show up in display functions until I restart the application. I insert new object through this method in the singleton class:
- (void)insertNewObject:(Care *)care
{
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:
[entity name] inManagedObjectContext:self.managedObjectContext];
NSString *fileName = care.pictureURL;
NSString *text = care.causeText;
NSDate *date = care.date;
NSData *imgData = care.imageData;
[newManagedObject setValue:fileName forKey:#"urlPath"];
[newManagedObject setValue:text forKey:#"name"];
[newManagedObject setValue:date forKey:#"date"];
[newManagedObject setValue:imgData forKey:#"imageData"];
// Save the context.
[self saveContext];
NSError *error = nil;
if (![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();
}
}
My count method is the way I can tell that the new object is not included until I restart the application. The count method is also in the singleton as well.
- (NSUInteger)countOfList
{
NSArray *fetchedData = [_fetchedResultsController fetchedObjects];
return [fetchedData count];
}
When calling singleton I use:
DataControllerSingleton *singletonData = [DataControllerSingleton singleDataController];
[singletonData insertNewObject:care];
managedObjectContext property:
.h:
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
.m:
#implementation DataControllerSingleton
#synthesize managedObjectContext = _managedObjectContext;
#synthesize managedObjectModel = _managedObjectModel;
#synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
Why will not my new object show up in ex count until I restart application?
Am I somehow using different threads with different contexts, or different fethedResultsController or different singleton (shouldnt be possible right?)??
I added these two lines, which are not included in the genereated CoreData Stack, and it now works fine.
In singleton header:
#interface DataControllerSingleton : NSObject <NSFetchedResultsControllerDelegate>
In implementation file,
(NSFetchedResultsController *)fetchedResultsController {
_fetchedResultsController.delegate = self;
As I understand from your question, you are using a table or similar.
If you want to update the table as soon as you save the context you need to:
Reload the data table [table reloadData];
or implement in the correct delegate methods of (take a look to How To Use NSFetchedResultsController)
If you follow the first option, you can just do a save in the context and call realod data on the table.
NSError *error = nil;
if (![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();
}
[table reloadData];
NOTE THAT YOU ARE CALLING THE SAVE TWICE Do it once. In this case I suppose that [self saveContext]; does the saving as above.
If you follow the second approach, the data reload woul be handled for you.
Hope that helps.
Edit
The delegate of your fetched results controller should be a view controller (the one that contains the table). Do not put it in your singleton!!