您知道有什么方法可以删除存储在Core Data中的所有条目吗?我的schema应该保持不变;我只想把它重置为空白。
Edit
我希望以编程方式做到这一点,这样用户就可以基本上按下重置按钮。
您知道有什么方法可以删除存储在Core Data中的所有条目吗?我的schema应该保持不变;我只想把它重置为空白。
Edit
我希望以编程方式做到这一点,这样用户就可以基本上按下重置按钮。
当前回答
下面这个版本可以删除每个表中的每条记录。
斯威夫特4
static func resetDatabase() {
do {
try dataStore.persistentStoreCoordinator.managedObjectModel.entities.forEach { (entity) in
if let name = entity.name {
let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: name)
let request = NSBatchDeleteRequest(fetchRequest: fetch)
try mainContext.execute(request)
}
}
try mainContext.save()
} catch {
print("error resenting the database: \(error.localizedDescription)")
}
}
其他回答
我从一个HomeViewController类的一个按钮事件的核心数据中删除所有数据: 这篇文章对我帮助很大,我想我也会有所贡献。
-(IBAction)buttonReset:(id)sender
{
NSLog(@"buttonReset Pressed");
//Erase the persistent store from coordinator and also file manager.
NSPersistentStore *store = [self.persistentStoreCoordinator.persistentStores lastObject];
NSError *error = nil;
NSURL *storeURL = store.URL;
[self.persistentStoreCoordinator removePersistentStore:store error:&error];
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:&error];
NSLog(@"Data Reset");
//Make new persistent store for future saves (Taken From Above Answer)
if (![self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// do something with the error
}
}
注意,为了调用self。我在主视图控制器中声明了一个属性。(不要担心我用来保存和加载的managedObjectContext。)
@property (nonatomic, retain) NSManagedObjectContext * managedObjectContext;
@property (nonatomic, retain) NSPersistentStoreCoordinator * persistentStoreCoordinator;
然后在AppDelegate ApplicationDidFinishLaunching下面创建一个HomeViewController:
homeViewController = [[HomeViewController alloc] initWithNibName:@"HomeViewController" bundle:nil];
homeViewController.managedObjectContext = self.managedObjectContext;
homeViewController.persistentStoreCoordinator = self.persistentStoreCoordinator;
龙道9+ Swift 2
删除所有实体中的所有对象
func clearCoreDataStore() {
let entities = managedObjectModel.entities
for entity in entities {
let fetchRequest = NSFetchRequest(entityName: entity.name!)
let deleteReqest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
do {
try context.executeRequest(deleteReqest)
} catch {
print(error)
}
}
}
删除持久存储文件并设置一个新的持久存储协调器?
如果需要删除所有对象且不删除备份文件,可以使用以下方法:
- (void)deleteAllObjectsInContext:(NSManagedObjectContext *)context
usingModel:(NSManagedObjectModel *)model
{
NSArray *entities = model.entities;
for (NSEntityDescription *entityDescription in entities) {
[self deleteAllObjectsWithEntityName:entityDescription.name
inContext:context];
}
}
- (void)deleteAllObjectsWithEntityName:(NSString *)entityName
inContext:(NSManagedObjectContext *)context
{
NSFetchRequest *fetchRequest =
[NSFetchRequest fetchRequestWithEntityName:entityName];
fetchRequest.includesPropertyValues = NO;
fetchRequest.includesSubentities = NO;
NSError *error;
NSArray *items = [context executeFetchRequest:fetchRequest error:&error];
for (NSManagedObject *managedObject in items) {
[context deleteObject:managedObject];
NSLog(@"Deleted %@", entityName);
}
}
注意它可能非常慢(取决于对象图中有多少对象)。
MagicalRecord使这非常简单。
[MyCoreDataObject MR_truncateAll];