该操作无法完成。 （可可错误512.）Coredata Iphone。 没有文件可以复制到文档文件夹中

Question

I'm working on a coredata project in a xcode 4.3 version for ios 5.1. I've made an ARC empty project with CoreData checkbox selected, following the methods add by xcode to manage model and modified by me following a tutorial for copying a prepopulate sqllite db to my app, the prepopulate db is in the resource group inside project folder and has the same name of model and project.

- (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:@"Prova1" withExtension:@"momd"];

NSLog(@"modelURL %@",modelURL);

    _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;
    }

NSString *storePath = [[[self applicationDocumentsDirectory] absoluteString] stringByAppendingPathComponent:@"Prova1.sqlite"];
 NSLog(@"storePath %@",storePath);

 NSURL *storeURL = [NSURL fileURLWithPath:storePath];
 NSLog(@"storeURL %@",storeURL);

 // Put down default db if it doesn't already exist
 NSFileManager *fileManager = [NSFileManager defaultManager];
 if (![fileManager fileExistsAtPath:storePath]) {
     NSString *defaultStorePath = [[NSBundle mainBundle] pathForResource:@"Prova1" ofType:@"sqlite"];
     if (defaultStorePath) {
          [fileManager copyItemAtPath:defaultStorePath toPath:storePath error:NULL];
     }
}/**/

/*NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Prova1.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];
}

here instead the viewcontroller's implementation with some field to interact with db.

@implementation ALCViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    self.textfied1 = [[UITextField alloc] initWithFrame:CGRectMake(200, 50, 300, 30)];
    self.textfied1.borderStyle = UITextBorderStyleRoundedRect;
    self.textfied1.delegate = self;
    [self.view addSubview:self.textfied1];

    self.textfied2 = [[UITextField alloc] initWithFrame:CGRectMake(200, 100, 300, 30)];
    self.textfied2.borderStyle = UITextBorderStyleRoundedRect;
    self.textfied2.delegate = self;
    [self.view addSubview:self.textfied2];

    self.salvaButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [self.salvaButton setFrame:CGRectMake(200, 150, 100, 20)];
    [self.salvaButton setTitle:@"salva" forState:UIControlStateNormal];
    [self.salvaButton addTarget:self action:@selector(salva:) forControlEvents:UIControlEventTouchDown];
    [self.view addSubview:self.salvaButton];

    self.cercaButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [self.cercaButton setFrame:CGRectMake(200, 200, 100, 20)];
    [self.cercaButton setTitle:@"Elenca" forState:UIControlStateNormal];
    [self.cercaButton addTarget:self action:@selector(cerca:) forControlEvents:UIControlEventTouchDown];
    [self.view addSubview:self.cercaButton];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    UIToolbar *toolbar = [[UIToolbar alloc] init];
    [toolbar setBarStyle:UIBarStyleBlackTranslucent];
    [toolbar sizeToFit];
    UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(doneClicked:)];

    if ([textField isEqual:self.textfied1]) {
        [doneButton setTag:1];
    }
    if ([textField isEqual:self.textfied2]) {
        [doneButton setTag:2];
    }

    [toolbar setItems:[NSArray arrayWithObjects:/*flexibleSpaceLeft,*/ doneButton, nil]];
    [textField setInputAccessoryView:toolbar];
    [textField setText:@""];
    [textField setTextColor:[UIColor blackColor]];
    [textField setFont:[UIFont systemFontOfSize:16]];/**/
    return YES;
}

- (void)doneClicked:(id)sender {
    UIButton *bSender = (UIButton *)sender;

    switch ([bSender tag]) {
    case 1: {
        [self.textfied1 resignFirstResponder];
    }
    break;
    case 2: {
        [self.textfied2 resignFirstResponder];
    }
    break;
    default:
    break;
    }
}

- (void)salva:(id)sender {
    ALCAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];

    NSManagedObject *newContact;
    newContact = [NSEntityDescription insertNewObjectForEntityForName:@"Stica" inManagedObjectContext:context];
    [newContact setValue:self.textfied1.text forKey:@"nome"];
    [newContact setValue:self.textfied2.text forKey:@"sfiga"];

    self.textfied1.text = @"";
    self.textfied2.text = @"";

    NSError *error;
    [context save:&error];
    //status.text = @”Contact saved”;
}

- (void)cerca:(id)sender {
    ALCAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Stica" inManagedObjectContext:context];
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    [request setEntity:entityDesc];

    /*NSPredicate *pred = [NSPredicate predicateWithFormat:@"(name = %@)", name.text];
 [request setPredicate:pred];*/

    NSError *error;

    NSArray *objects = [context executeFetchRequest:request error:&error];

    if ([objects count] == 0) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Risultati" message:@"Vuoto" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [alert show];
    } 
    else {
        for (NSManagedObject *object in objects) {
            NSMutableString *string = [[NSMutableString alloc] initWithFormat:@"%@ - %@",[object valueForKey:@"nome"],[object valueForKey:@"sfiga"]];
            NSLog(@"%@",string);
        }
    }
}

@end

The problems come when i try to see the records stored inside the db, in fact the error pushing the button named "Elenca", xcode give me this error:

Unresolved error Error Domain=NSCocoaErrorDomain Code=512 
"The operation couldn’t be completed. (Cocoa error 512.)" 
UserInfo=0x6e7a120 {
    reason=Failed to create file; code = 2
}, 
{
    reason = "Failed to create file; code = 2";
}

I've tried also to output some variables:

storePath file:/localhost/Users/winimac01/Library/Application%20Support/iPhone%20Simulator/5.1/Applications/7733DC6C-CE52-4EB4-9A60-26962F7AEDD9/Documents/Prova1.sqlite

storeURL file:/localhost/Users/winimac01/Library/Application%2520Support/iPhone%2520Simulator/5.1/Applications/7733DC6C-CE52-4EB4-9A60-26962F7AEDD9/Documents/Prova1.sqlite -- file://localhost/

modelURL file://localhost/Users/winimac01/Library/Application%20Support/iPhone%20Simulator/5.1/Applications/7733DC6C-CE52-4EB4-9A60-26962F7AEDD9/Prova1.app/Prova1.momd/ 2012-10-22 12:30:46.598 Prova1[2479:fb03] () isEditable 0, entities { Meco = "() name Meco, managedObjectClassName NSManagedObject, renamingIdentifier Meco, isAbstract 0, superentity name (null), properties {\\n miracoli = \\"(), name miracoli, isOptional 1, isTransient 0, entity Meco, renamingIdentifier miracoli, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, attributeType 700 , attributeValueClassName NSString, defaultValue (null)\\";\\n morte = \\"(), name morte, isOptional 1, isTransient 0, entity Meco, renamingIdentifier morte, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, attributeType 700 , attributeValueClassName NSString, defaultValue (null)\\";\\n nome = \\"(), name nome, isOptional 1, isTransient 0, entity Meco, renamingIdentifier nome, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, attributeType 700 , attributeValueClassName NSString, defaultValue (null)\\";\\n relationship = \\"(), name relationship, isOptional 1, isTransient 0, entity Meco, renamingIdentifier relationship, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, destination entity Stica, inverseRelationship relationship, minCount 1, maxCount 1, isOrdered 0, deleteRule 1\\";\\n}, subentities (null), userInfo {\\n}, versionHashModifier (null)"; Stica = "() name Stica, managedObjectClassName NSManagedObject, renamingIdentifier Stica, isAbstract 0, superentity name (null), properties {\\n nome = \\"(), name nome, isOptional 1, isTransient 0, entity Stica, renamingIdentifier nome, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, attributeType 700 , attributeValueClassName NSString, defaultValue (null)\\";\\n relationship = \\"(), name relationship, isOptional 1, isTransient 0, entity Stica, renamingIdentifier relationship, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, destination entity Meco, inverseRelationship relationship, minCount 1, maxCount 1, isOrdered 0, deleteRule 1\\";\\n sfiga = \\"(), name sfiga, isOptional 1, isTransient 0, entity Stica, renamingIdentifier sfiga, validation predicates (\\n), warnings (\\n), versionHashModifier (null)\\n userInfo {\\n}, attributeType 700 , attributeValueClassName NSString, defaultValue (null)\\";\\n}, subentities (null) , userInfo {\\n}, versionHashModifier (null)"; }, fetch request templates { }

and I don't know why storeURL has that form, what is the " -- file://localhost/" ath the end of the string? Why can't create the .sqlite file? and wich is the right way to fix the problem? I've already tried to reset the simulator and the paths are correct...

Thanks in advance

edit1: the tut that i've studied is this

edit2: A possible solution that works is change this piece of code:

NSString *storePath = [[[self applicationDocumentsDirectory] absoluteString] stringByAppendingPathComponent:@"Prova1.sqlite"];
NSURL *storeURL = [NSURL fileURLWithPath:storePath];

 // Put down default db if it doesn't already exist
 NSFileManager *fileManager = [NSFileManager defaultManager];
 if (![fileManager fileExistsAtPath:storePath]) {
     NSString *defaultStorePath = [[NSBundle mainBundle] pathForResource:@"Prova1" ofType:@"sqlite"];

     if (defaultStorePath) {
         [fileManager copyItemAtPath:defaultStorePath toPath:storePath error:NULL];
     }
 }/**/

with:

NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Prova1.sqlite"];

// Put down default db if it doesn't already exist
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:storePath]) {
    NSURL *defaultStoreURL = [[NSBundle mainBundle] URLForResource:@"Prova1" withExtension:@"sqlite"];

    if (defaultStoreURL) {
        [fileManager copyItemAtURL:defaultStoreURL toURL:storeURL error:NULL];
    }
}/**/

Answer 1

The usage of absoluteString in

NSString *storePath = [[[self applicationDocumentsDirectory] absoluteString] stringByAppendingPathComponent:@"Prova1.sqlite"];

is not correct. It creates a string

file:/localhost/Users/winimac01/...

where "file:" is actually part of the string, so this file surely does not exist.

Using path instead should fix the problem:

NSString *storePath = [[[self applicationDocumentsDirectory] path] stringByAppendingPathComponent:@"Prova1.sqlite"];