Skip to main content

CoreData

快速开始

  1. 新建Model

  1. 设置Model

  1. 新建DataController

准备好Model数据,此时并没有加载

let container = NSPersistentContainer(name: "notify")

加载数据

container.loadPersistentStores{ description, error in
if let error = error {
print("Core Data fail to load, \(error.localizedDescription)")
}
}
import CoreData
import Foundation

class DataController: ObservableObject {
let container = NSPersistentContainer(name: "notify")

init(){
container.loadPersistentStores{ description, error in
if let error = error {
print("Core Data fail to load, \(error.localizedDescription)")
}
}
}
}
  1. App中绑定
import SwiftUI

@main
struct notifyApp: App {

// 注册生命周期
@UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

// 绑定CoreData
@StateObject private var dataController = DataController()

var body: some Scene {
WindowGroup {
ContentView()
.environment(\.managedObjectContext, dataController.container.viewContext)
}
}
}
  1. View中使用
@FetchRequest(entity: Notify.entity(),sortDescriptors: []) var notifies: FetchedResults<Notify>

保存数据

let notify = Notify(context: moc)
notify.title = "demo Title"
notify.id = UUID()
try? moc.save()

删除数据

offset = 1
let notify = notifies[offset]
moc.delete(notify)

一些报错

Thread 1: "executeFetchRequest:error: A fetch request must have an entity."

在有多个实体的情况下,@FetchRequest需要注明entity参数使用的是那个entity,只有一个entity的时候可以省略,如下所示。

@FetchRequest(entity: Finance.entity(),  sortDescriptors: []) var finance: FetchedResults<Finance>