core-data

问题 I have an app that allows users to save favorites. I am using Core Data to store the favorites as managed objects. I have written some code to prevent the possibility of storing duplicates, but am wondering if there is a better way to do so. Each favorite object has an ID field that is unique. In the following code I am simply looping through and checking the ID field, and if the value already exists, setting a flag value to true, and breaking out of the loop. -(BOOL)addFavorite{ BOOL

问题 I have an app that allows users to save favorites. I am using Core Data to store the favorites as managed objects. I have written some code to prevent the possibility of storing duplicates, but am wondering if there is a better way to do so. Each favorite object has an ID field that is unique. In the following code I am simply looping through and checking the ID field, and if the value already exists, setting a flag value to true, and breaking out of the loop. -(BOOL)addFavorite{ BOOL

问题 I have implemented NSPersistentCloudKitContainer to get my data synced to CloudKit , I would like to know that the sync is finished and there is no other change pending to be synced. When I tried reinstalling the app, I start getting my data back from CloudKit and it started printing certain logs in the console. It takes around 30 seconds to get all my data back from the CloudKit. Some of the logs mention about NSCloudKitMirroringDelegate . It looks like NSCloudKitMirroringDelegate knows

问题 I have a SwiftUI project with Core Data. The data model is a simple one-to-many and two primary views which each have a textfield at the top and a button to add a new item to the list view below. The first view is for the One side of the relation and the second for the Many. So, the NavigationLink in the first opens the second and passes the One object. Pretty standard stuff, it would seem. The methodology for creating the One works and the list below gets updated immediately when the managed

问题 I have a SwiftUI project with Core Data. The data model is a simple one-to-many and two primary views which each have a textfield at the top and a button to add a new item to the list view below. The first view is for the One side of the relation and the second for the Many. So, the NavigationLink in the first opens the second and passes the One object. Pretty standard stuff, it would seem. The methodology for creating the One works and the list below gets updated immediately when the managed

问题 I am have an entity in core data and I try to update it from two different context. I am storing managedObjectID of my managed object which I need to update as it is thread safe. Before updating my object I refresh the object to avoid merge conflict. Here is my code: context1.performBlock { let myObject = context1.objectWithID(managedObjectId) context1.refreshObject(myObject, mergeChanges: true) myObject.property1 = newValue } Notice that I haven't saved the context here, as I want to commit

问题 I want to display data fetched from Core Data in a widget. But @FetchRequest doesn’t work on widgets. As I understand, we have to create an app group and make a shared persistent container. What I want to know is how to read (fetch) data on widgets from that shared persistent container or simply, how to display data fetched from Core Data in widgets . 回答1: First you need to create an AppGroup which will be used to create a Core Data Persistent Container (here is a good explanation how to do

问题 I want to display data fetched from Core Data in a widget. But @FetchRequest doesn’t work on widgets. As I understand, we have to create an app group and make a shared persistent container. What I want to know is how to read (fetch) data on widgets from that shared persistent container or simply, how to display data fetched from Core Data in widgets . 回答1: First you need to create an AppGroup which will be used to create a Core Data Persistent Container (here is a good explanation how to do

问题 I am trying to create a very basic app with two views. The main view displays CoreData objects in a NavigationView and has a toolbar button to open an "add item" modal sheet. The "add item" sheet should be able to insert a new CoreData object and dismiss itself. What I am observing is that the modal sheet can be dismissed as long as it doesn't insert a CoreData object, but once it does interact with CoreData, all my attempts to dismiss the sheet no longer work. Also, when the sheet creates a

问题 i am currently working with SwiftUI and CoreData . Situation: I have a User Detail View with a Delete Button at the Bottom. When pressed, the Core Data Entry of the User is getting deleted and the App Navigation goes back to the Root Navigation View, which is a List of all Users. Problem: Every Time the Delete Button is clicked the App crashes with the following Error Message : *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[User timeCreated]: