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
iOS 10 + Swift 3解决方案:
func clearCoreDataStore() {
let delegate = UIApplication.shared.delegate as! AppDelegate
let context = delegate.persistentContainer.viewContext
for i in 0...delegate.persistentContainer.managedObjectModel.entities.count-1 {
let entity = delegate.persistentContainer.managedObjectModel.entities[i]
do {
let query = NSFetchRequest<NSFetchRequestResult>(entityName: entity.name!)
let deleterequest = NSBatchDeleteRequest(fetchRequest: query)
try context.execute(deleterequest)
try context.save()
} catch let error as NSError {
print("Error: \(error.localizedDescription)")
abort()
}
}
}
遍历所有核心数据实体并清除它们
其他回答
从fileURLPath中删除sqlite,然后构建。
删除持久存储文件并设置一个新的持久存储协调器?
下面是一个稍微简化的版本,减少了对AppDelegate self的调用,并且去掉了排名最高的答案中的最后一点代码。此外,我得到了一个错误“对象的持久存储无法从这个NSManagedObjectContext的协调器”,所以只需要添加回来。
NSPersistentStoreCoordinator *storeCoordinator = [self persistentStoreCoordinator];
NSPersistentStore *store = [[storeCoordinator persistentStores] lastObject];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"dataModel"];
NSError *error;
[storeCoordinator removePersistentStore:store error:&error];
[[NSFileManager defaultManager] removeItemAtPath:storeURL.path error:&error];
[_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error];
if (storeCoordinator != nil) {
_managedObjectContext = [[NSManagedObjectContext alloc] init];
[_managedObjectContext setPersistentStoreCoordinator:storeCoordinator];
}
Swift 4/5, iOS 9+
重新构建整个CoreData SQLite文件将确保擦除所有数据,因此删除所有实体。只需调用deleteAndRebuild()。
class CoreDataStack {
// Change this
static let datamodelName = "ProjectName"
static let storeType = "sqlite"
static let persistentContainer = NSPersistentContainer(name: datamodelName)
private static let url: URL = {
let url = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0].appendingPathComponent("\(datamodelName).\(storeType)")
assert(FileManager.default.fileExists(atPath: url.path))
return url
}()
static func loadStores() {
persistentContainer.loadPersistentStores(completionHandler: { (nsPersistentStoreDescription, error) in
if let error = error {
fatalError(error.localizedDescription)
}
})
}
static func deleteAndRebuild() {
try! persistentContainer.persistentStoreCoordinator.destroyPersistentStore(at: url, ofType: storeType, options: nil)
loadStores()
}
}
我采取了Grouchal的代码,为了加快速度,我使用了并发模式的枚举(NSEnumerationConcurrent),它比for循环快了一点(在我的应用程序中,我为测试人员添加了这个功能,以便他们可以清除数据和做测试用例,而不是删除和安装应用程序)
- (void)resetObjects
{
[self deleteAllObjectsInEntity:@"Entity1"];
[self deleteAllObjectsInEntity:@"Entity2"];
[self deleteAllObjectsInEntity:@"Entity3"];
[self deleteAllObjectsInEntity:@"Entity4"];
}
-(void) deleteAllObjectsInEntity:(NSString*) entityName
{
MainDataContext *coreDataContext = [MainDataContext sharedInstance];
NSManagedObjectContext *currentContext = coreDataContext.managedObjectContext;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:currentContext];
[fetchRequest setEntity:entity];
NSError *error;
NSArray *items = [currentContext executeFetchRequest:fetchRequest error:&error];
[items enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(NSManagedObject * obj, NSUInteger idx, BOOL *stop) {
[currentContext deleteObject:obj];
}];
if (![currentContext save:&error]) {
NSLog(@"Error deleting %@ - error:%@",entityName,error);
}
}