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
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()
}
}
其他回答
这里是清洗核心数据的组合解决方案。
- (void)deleteAllObjectsInCoreData
{
NSArray *allEntities = self.managedObjectModel.entities;
for (NSEntityDescription *entityDescription in allEntities)
{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity:entityDescription];
fetchRequest.includesPropertyValues = NO;
fetchRequest.includesSubentities = NO;
NSError *error;
NSArray *items = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (error) {
NSLog(@"Error requesting items from Core Data: %@", [error localizedDescription]);
}
for (NSManagedObject *managedObject in items) {
[self.managedObjectContext deleteObject:managedObject];
}
if (![self.managedObjectContext save:&error]) {
NSLog(@"Error deleting %@ - error:%@", entityDescription, [error localizedDescription]);
}
}
}
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)。
似乎有两种方法:
假设您的核心数据堆栈有一个典型的单例。
import CoreData
public let core = Core.shared
public final class Core {
static let shared = Core()
var container: NSPersistentContainer!
private init() {
container = NSPersistentContainer(name: "stuff")
//deleteSql()
container.loadPersistentStores { storeDescription, error in
if let error = error { print("Error loading... \(error)") }
}
//deleteAll()
}
func saveContext() { // typical save helper
if container.viewContext.hasChanges {
do { try container.viewContext.save()
} catch { print("Error saving... \(error)") }
}
}
然后……
func deleteSql() {
let url = FileManager.default.urls(
for: .applicationSupportDirectory,
in: .userDomainMask)[0].appendingPathComponent( "stuff.sqlite" )
guard FileManager.default.fileExists(atPath: url.path) else {
print("nothing to delete!")
return
}
do {
try container.persistentStoreCoordinator.destroyPersistentStore(
at: url, ofType: "sqlite", options: nil)
print("totally scorched the sql file. you DO now have to LOAD again")
}
catch {
print("there was no sql file there!")
}
}
func deleteAll() { // courtesy @Politta
for e in container.persistentStoreCoordinator.managedObjectModel.entities {
let r = NSBatchDeleteRequest(
fetchRequest: NSFetchRequest(entityName: e.name ?? ""))
let _ = try? container.viewContext.execute(r)
}
saveContext()
print("conventionally deleted everything from within core data. carry on")
}
}
.
1. 焦化SQL文件
感谢优秀的@J。能源部的答案。您完全销毁了sql文件。
你必须这样做
在加载核心数据之前,即在创建容器之后,但是 在真正载入商店之前。)
(注意示例代码“//deleteSql()”就在初始化之前。)
2. 逐个删除核心数据中的所有内容
感谢精彩的@Politta回答。一旦core data启动并运行,就可以随时执行此操作。
(注意示例代码“//deleteAll()”是在初始化之后。)
方法一在开发过程中可能更有用。方法二在生产中可能更有用(在相对不常见的情况下,由于某种原因需要擦除所有内容)。
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)
}
}
}
适用于所有版本。传递实体名称并遍历删除所有条目并保存上下文。
func deleteData(entityToFetch: String, completion: @escaping(_ returned: Bool) ->()) {
var context = NSManagedObjectContext()
if #available(iOS 10.0, *) {
context = self.persistentContainer.viewContext
} else {
context = self.managedObjectContext
}
let fetchRequest = NSFetchRequest<NSFetchRequestResult>()
fetchRequest.entity = NSEntityDescription.entity(forEntityName: entityToFetch, in: context)
fetchRequest.includesPropertyValues = false
do {
let results = try context.fetch(fetchRequest) as! [NSManagedObject]
for result in results {
context.delete(result)
}
try context.save()
completion(true)
} catch {
completion(false)
print("fetch error -\(error.localizedDescription)")
}
}