当我使用核心数据模板创建iOS 11应用程序时，它在AppDelete.m中自动生成了以下代码。
synthesize persistentContainer = _persistentContainer;
- (NSPersistentContainer *)persistentContainer {
// The persistent container for the application. This implementation creates and returns a container, having loaded the store for the application to it.
@synchronized (self) {
if (_persistentContainer == nil) {
_persistentContainer = [[NSPersistentContainer alloc] initWithName:@"My_History"];
[_persistentContainer loadPersistentStoresWithCompletionHandler:^(NSPersistentStoreDescription *storeDescription, NSError *error) {
if (error != nil) {
// 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.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
NSLog(@"Unresolved error %@, %@", error, error.userInfo);
abort();
}
}];
}
}
return _persistentContainer;
}
- (void)saveContext {
NSManagedObjectContext *context = self.persistentContainer.viewContext;
NSError *error = nil;
if ([context hasChanges] && ![context 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();
}
我想添加一个 Today 和 iMessage 扩展，用于访问核心数据中的历史记录。根据我所读的内容，如果存在此数据，我需要将其迁移到共享应用程序容器。我该怎么做？
代码位于目标 C 中。
我读过其他与此相关的问题，但所有这些问题似乎都是在苹果改变核心数据的工作方式以使其更容易之前。正如您在代码中看到的那样，我从未指定数据存储的确切文件名是什么。我看到的每个示例都有类似"My_History.sqllite"的内容。我什至不知道我的数据库是否是一个sql lite数据库，它只是由该代码创建的。
solidsnake4444 的答案拯救了我的一天。这是 Swift 5.0 版本。
lazy var persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "MyApp")
let storeURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.com.my.app")!.appendingPathComponent("MyApp.sqlite")
var defaultURL: URL?
if let storeDescription = container.persistentStoreDescriptions.first, let url = storeDescription.url {
defaultURL = FileManager.default.fileExists(atPath: url.path) ? url : nil
}
if defaultURL == nil {
container.persistentStoreDescriptions = [NSPersistentStoreDescription(url: storeURL)]
}
container.loadPersistentStores(completionHandler: { [unowned container] (storeDescription, error) in
if let error = error as NSError? {
fatalError("Unresolved error (error), (error.userInfo)")
}
if let url = defaultURL, url.absoluteString != storeURL.absoluteString {
let coordinator = container.persistentStoreCoordinator
if let oldStore = coordinator.persistentStore(for: url) {
do {
try coordinator.migratePersistentStore(oldStore, to: storeURL, options: nil, withType: NSSQLiteStoreType)
} catch {
print(error.localizedDescription)
}
// delete old store
let fileCoordinator = NSFileCoordinator(filePresenter: nil)
fileCoordinator.coordinate(writingItemAt: url, options: .forDeleting, error: nil, byAccessor: { url in
do {
try FileManager.default.removeItem(at: url)
} catch {
print(error.localizedDescription)
}
})
}
}
})
return container
}()
我最终让它执行以下操作。sqlite文件实际上是我的init的名称加上最后的.sqlite。
+ (NSPersistentContainer*) GetPersistentContainer {
//Init the store.
NSPersistentContainer *_persistentContainer = [[NSPersistentContainer alloc] initWithName:@"Test_App"];
//Define the store url that is located in the shared group.
NSURL* storeURL = [[[NSFileManager defaultManager] containerURLForSecurityApplicationGroupIdentifier:@"group.Test_App"] URLByAppendingPathComponent:@"Test_App.sqlite"];
//Determine if we already have a store saved in the default app location.
BOOL hasDefaultAppLocation = [[NSFileManager defaultManager] fileExistsAtPath: _persistentContainer.persistentStoreDescriptions[0].URL.path];
//Check if the store needs migration.
BOOL storeNeedsMigration = hasDefaultAppLocation && ![_persistentContainer.persistentStoreDescriptions[0].URL.absoluteString isEqualToString:storeURL.absoluteString];
//Check if the store in the default location does not exist.
if (!hasDefaultAppLocation) {
//Create a description to use for the app group store.
NSPersistentStoreDescription *description = [[NSPersistentStoreDescription alloc] init];
//set the automatic properties for the store.
description.shouldMigrateStoreAutomatically = true;
description.shouldInferMappingModelAutomatically = true;
//Set the url for the store.
description.URL = storeURL;
//Replace the coordinator store description with this description.
_persistentContainer.persistentStoreDescriptions = [NSArray arrayWithObjects:description, nil];
}
//Load the store.
[_persistentContainer loadPersistentStoresWithCompletionHandler:^(NSPersistentStoreDescription *storeDescription, NSError *error) {
//Check that we do not have an error.
if (error == nil) {
//Check if we need to migrate the store.
if (storeNeedsMigration) {
//Create errors to track migration and deleting errors.
NSError *migrateError;
NSError *deleteError;
//Store the old location URL.
NSURL *oldStoreURL = storeDescription.URL;
//Get the store we want to migrate.
NSPersistentStore *store = [_persistentContainer.persistentStoreCoordinator persistentStoreForURL: oldStoreURL];
//Set the store options.
NSDictionary *storeOptions = @{ NSSQLitePragmasOption : @{ @"journal_mode" : @"WAL" } };
//Migrate the store.
NSPersistentStore *newStore = [_persistentContainer.persistentStoreCoordinator migratePersistentStore: store toURL:storeURL options:storeOptions withType:NSSQLiteStoreType error:&migrateError];
//Check that the store was migrated.
if (newStore && !migrateError) {
//Remove the old SQLLite database.
[[[NSFileCoordinator alloc] init] coordinateWritingItemAtURL: oldStoreURL options: NSFileCoordinatorWritingForDeleting error: &deleteError byAccessor: ^(NSURL *urlForModifying) {
//Create a remove error.
NSError *removeError;
//Delete the file.
[[NSFileManager defaultManager] removeItemAtURL: urlForModifying error: &removeError];
//If there was an error. Output it.
if (removeError) {
NSLog(@"%@", [removeError localizedDescription]);
}
}
];
//If there was an error. Output it.
if (deleteError) {
NSLog(@"%@", [deleteError localizedDescription]);
}
}
}
} else {
// 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.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
NSLog(@"Unresolved error %@, %@", error, error.userInfo);
abort();
}
}];
//Return the container.
return _persistentContainer;
}
当移动NSPersistentCloudKitContainer时，这对我有用。需要注意的几件事：
- 您需要确保在持久存储描述上设置
cloudKitContainerOptions，否则同步将停止工作 - 不要调用
migratePersistentStore否则您最终会得到重复的记录，而是使用replacePersistentStore- 有关更多信息，请参阅此线程 - 成功迁移后，您可能希望删除旧数据库，
destroyPersistentStore听起来很有希望，但似乎并没有真正删除文件 - 请参阅此问题
struct PersistenceController {
static let shared = PersistenceController()
let container: NSPersistentCloudKitContainer
init(inMemory: Bool = false) {
container = NSPersistentCloudKitContainer(name: "MyCuteDB")
if inMemory {
container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
} else {
// Use App Groups so app and extensions can access database
let sharedStoreURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.com.yourdomain.yourapp")!.appendingPathComponent("(container.name).sqlite")
let defaultStoreURL = container.persistentStoreDescriptions.first!.url! //the URL always starts out in the default location
// move database to shared location if needed
if FileManager.default.fileExists(atPath: defaultStoreURL.path) && !FileManager.default.fileExists(atPath: sharedStoreURL.path) {
let coordinator = container.persistentStoreCoordinator
do {
try coordinator.replacePersistentStore(at: sharedStoreURL, destinationOptions: nil, withPersistentStoreFrom: defaultStoreURL, sourceOptions: nil, ofType: NSSQLiteStoreType)
try? coordinator.destroyPersistentStore(at: defaultStoreURL, ofType: NSSQLiteStoreType, options: nil)
// destroyPersistentStore says it deletes the old store but it actually truncates so we'll manually delete the files
NSFileCoordinator(filePresenter: nil).coordinate(writingItemAt: defaultStoreURL.deletingLastPathComponent(), options: .forDeleting, error: nil, byAccessor: { url in
try? FileManager.default.removeItem(at: defaultStoreURL)
try? FileManager.default.removeItem(at: defaultStoreURL.deletingLastPathComponent().appendingPathComponent("(container.name).sqlite-shm"))
try? FileManager.default.removeItem(at: defaultStoreURL.deletingLastPathComponent().appendingPathComponent("(container.name).sqlite-wal"))
try? FileManager.default.removeItem(at: defaultStoreURL.deletingLastPathComponent().appendingPathComponent("ckAssetFiles"))
})
} catch {
//TODO: Handle error
}
}
// change URL from default to shared location
container.persistentStoreDescriptions.first!.url = sharedStoreURL
let description = container.persistentStoreDescriptions.first!
description.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.com.yourdomain.yourapp")
}
container.loadPersistentStores { description, error in
//TODO: Handle error
}
container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
container.viewContext.automaticallyMergesChangesFromParent = true
}
}
更新：
要迁移现有的持久存储，NSPersistentContainer包含persistentStoreCoordinator，NSPersistentStoreCoordinator的实例。这将公开migratePersistentStore:toURL:options:withType:error:迁移持久存储的方法。
我会做以下几点：
// Get the reference to the persistent store coordinator
let coordinator = persistentContainer.persistentStoreCoordinator
// Get the URL of the persistent store
let oldURL = persistentContainer.persistentStoreDescriptions.url
// Get the URL of the new App Group location
let newURL = NSFileManager.defaultManager().containerURLForSecurityApplicationGroupIdentifier("YOUR_APP_GROUP")
// Get the reference to the current persistent store
let oldStore = coordinator.persistentStore(for: oldURL)
// Migrate the persistent store
do {
try coordinator.migratePersistentStore(oldStore, to: newURL, options: nil, withType: NSSQLiteStoreType)
} catch {
// ERROR
}
请注意，上述内容尚未经过测试，我尚未处理可选，因此不完整。另外，我很抱歉它在 Swift 中。希望你很容易在Objective-C中编写等效的东西。
源语言：
下面概述了如何创建与非默认位置中的持久存储的NSPersistentContainer接口。
NSPersistentContainer公开了defaultDirectoryURL，并指出：
此方法返回一个依赖于平台
NSURL在该，在该持久 商店将位于或当前位于。此方法可以是 在NSPersistentContainer的子类中被覆盖。
如果使用containerURLForSecurityApplicationGroupIdentifier将defaultDirectoryURLNSPersistentContainer子类化并定义为应用组目录，则应该能够访问应用程序和扩展之间的容器(假设它们具有相同的应用组权利(。
NSPersistentContainer还公开了persistentStoreDescriptions，其中还具有 URL 实例。同样，您可以在调用loadPersistentStoresWithCompletionHandler:之前将其更新为应用组 URL。
请注意，我没有使用NSPersistentContainer，并且不知道这种共享是否会导致任何并发问题。