Question

我正在使用coreData，具有一对多的实现，我有一个文件夹实体和一个文件实体。文件夹可以包含许多文件，依此类推。

所以，我有两个ViewControllers，FolderViewController和FileViewController，它们分别包含文件夹和文件。现在我有一个modalView，可以从文件夹和文件viewcontroller访问。在这个VC中，我有一个重置所有数据的按钮。所以当我点击这个时，我想要重置所有数据。

我使用了这段代码，这个函数是用appdelegate.m编写的，并从我的VC中调用。

- (void)resetToDefault
{
    NSError * error;
    // retrieve the store URL
    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];
    //that's it !

    NSLog(@"buttonReset Pressed");
}

因此，当我关闭View时单击resetButton后，我收到此错误

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Object's persistent store is not reachable from this NSManagedObjectContext's coordinator'

那么如何解决这个问题。

此致兰吉特

Answer 1

我已经解决了这个问题，下面是代码，

此功能已在appdelegate.m中编写

- (void) resetApplicationModel
{
    NSError *error;
    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"AppName.sqlite"];
    [[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil];
    for (NSManagedObject *ct in [self.managedObjectContext registeredObjects]) {
        [self.managedObjectContext deleteObject:ct];
    }

    //Make new persistent store for future saves   
    if (![self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
        // do something with the error
    }  
}

在我的SettingsViewController中，我在resetbutton上调用它，点击这样。

- (void)resetButtonclicked
{
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
        [appDelegate resetApplicationModel];  
}

此致兰吉特。

Answer 2

    NSPersistentStore *store = [self.persistentStoreCoordinator.persistentStores lastObject];
    NSError *error;
    NSURL *storeURL = store.URL;
    NSPersistentStoreCoordinator *storeCoordinator = self.persistentStoreCoordinator;
    [storeCoordinator removePersistentStore:store error:&error];
    [[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:&error];
//    Then, just add the persistent store back to ensure it is recreated properly.    
    if (![self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

如何以一对多关系清除/重置所有核心数据

2 个答案: