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我的工作Objective-C與CoreData，我得到下面的錯誤是...一類的NSManagedObject「的NSManagedObject必須有一個有效NSEntityDescription
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'An NSManagedObject of class 'NSManagedObject' must have a valid NSEntityDescription.'
我加CoreData到我的項目。我在viewControllerA中創建saveData方法，我在viewControllerB中調用它。
在這種情況下，我得到錯誤，如果我調用viewDidLoad中的saveData方法viewControllerA它工作正常。
In AppDelegate.h
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
In AppDelegate.m
#pragma mark - Core Data stack
@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
- (NSURL *)applicationDocumentsDirectory {
// The directory the application uses to store the Core Data store file. This code uses a directory named "com.brninfotech._607_introToCoreDataFinal" in the application's documents directory.
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"VehicleNumberDataBase" withExtension:@"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
// The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it.
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
// Create the coordinator and store
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"VehicleNumberDataBase.sqlite"];
// NSLog(@"StoreURL is %@",storeURL);
NSError *error = nil;
NSString *failureReason = @"There was an error creating or loading the application's saved data.";
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
// Replace this 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();
}
return _persistentStoreCoordinator;
}
- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}
#pragma mark - Core Data Saving support
- (void)saveContext {
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
NSError *error = 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();
}
}
}
in viewControllerA viewDidLoad
self.ad = (AppDelegate *)[[UIApplication sharedApplication]delegate];
self.VehicleNumberED = [NSEntityDescription entityForName:@"VehicleNumberEntity" inManagedObjectContext:self.ad.managedObjectContext];
- (void)saveData {
NSManagedObject * managedObj = [[NSManagedObject alloc]initWithEntity:self.VehicleNumberED insertIntoManagedObjectContext:self.ad.managedObjectContext];
[managedObj setValue:self.textFieldString forKey:@"vehicleNumberAtt"];
NSError * errorObj;
[self.ad.managedObjectContext save:&errorObj];
if (errorObj) {
NSLog(@"Something goes wrong");
}else {
NSLog(@"Saved Successfully");
}
NSFetchRequest * fetReq = [NSFetchRequest fetchRequestWithEntityName:@"VehicleNumberEntity"];
NSError * fetchErrorObj;
self.storedDataArray = [self.ad.managedObjectContext executeFetchRequest:fetReq error:&fetchErrorObj];
NSLog(@"array count is %lu", self.storedDataArray.count);
for (int i=0; i<self.storedDataArray.count; i++) {
self.storedManagedObj = [self.storedDataArray objectAtIndex:i];
self.vehicleNumberArray = [self.storedManagedObj valueForKey:@"vehicleNumberAtt"];
}
NSLog(@"Vehicle number is : %@", [self.storedManagedObj valueForKey:@"vehicleNumberAtt"]);
}
in ViewVontrollerB
- (IBAction)saveVehicleNumberButton:(UIButton *)sender {
VehicleDetailsViewController *vedvc = [[VehicleDetailsViewController alloc]init];
vedvc = [self.storyboard instantiateViewControllerWithIdentifier:@"VeDVC"];
vedvc.textFieldString = self.vehicleNumberTextField.text;
[vedvc saveData];
[self.navigationController pushViewController:vedvc animated:YES];
}