模型更改后,擦除存储在CoreData中的所有数据

let persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: managedObjectModel)
let url = NSPersistentContainer.defaultDirectoryURL()
let storeUrl = url.appendingPathComponent("YourApp.sqlite")
do {
    try persistentStoreCoordinator.destroyPersistentStore(at: storeUrl, ofType: NSSQLiteStoreType, options: nil)
} catch {
    print("Error: \(error)")
}

let container = NSPersistentContainer(name: "YourApp")
container.loadPersistentStores { (storeDescription, error) in
    if let error = error {
        print("Error: \(error)")
    }
}

let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "YourEntity")
let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
do {
    try container.persistentStoreCoordinator.execute(deleteRequest, with: container.viewContext)
} catch {
    print("Error: \(error)")
}