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

接受的答案是正确的,通过NSFileManager删除URL是正确的,但正如在iOS 5+编辑中所述,持久存储不仅仅由一个文件表示。对于SQLite存储,它是*。sqlite, *。Sqlite-shm和*。sqlite-wal……幸运的是,自从iOS 7+我们可以使用方法

[NSPersistentStoreCoordinator + removeUbiquitousContentAndPersistentStoreAtURL选项:错误:):

为了处理删除,代码应该是这样的:

NSPersistentStore *store = ...;
NSError *error;
NSURL *storeURL = store.URL;
NSString *storeName = ...;
NSPersistentStoreCoordinator *storeCoordinator = ...;
[storeCoordinator removePersistentStore:store error:&error];
[NSPersistentStoreCoordinator removeUbiquitousContentAndPersistentStoreAtURL:storeURL.path options:@{NSPersistentStoreUbiquitousContentNameKey: storeName} error:&error];

我写了一个clearStores方法,遍历每个存储,并从协调器和文件系统中删除它(错误处理不考虑):

NSArray *stores = [persistentStoreCoordinator persistentStores];

for(NSPersistentStore *store in stores) {
    [persistentStoreCoordinator removePersistentStore:store error:nil];
    [[NSFileManager defaultManager] removeItemAtPath:store.URL.path error:nil];
}

[persistentStoreCoordinator release], persistentStoreCoordinator = nil;

这个方法在一个coreDataHelper类中,它负责在persistentStore为nil时创建persistentStore。

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)
        }
    }
}

迅速的解决方案:

class func deleteAllManagedObjects() {

        let modelURL = NSBundle.mainBundle().URLForResource("some string", withExtension: "mom")
        let mom = NSManagedObjectModel(contentsOfURL: modelURL)

        for entityName in mom.entitiesByName.keys {
            let fr = NSFetchRequest(entityName: entityName as String)
            let a = Utility.managedObjectContext().executeFetchRequest(fr, error: nil) as [NSManagedObject]
            for mo in a {
                Utility.managedObjectContext().deleteObject(mo)
            }
        }

        Utility.managedObjectContext().save(nil)
    }

Swift 5.1解决方案

public static func reset() {
    let coordinator = _persistentContainer.persistentStoreCoordinator
    for store in coordinator.persistentStores where store.url != nil {
        try? coordinator.remove(store)
        try? FileManager.default.removeItem(atPath: store.url!.path)
    }
}