1 建立自己的CoreDataStack

ViewController 指的是导航层中的第一个视图

1.1 CoreDataStack.swift

** File\New\File...**, 选 iOS\Source\Swift。取名 **CoreDataStack.swift **。

import CoreData

class CoreDataStack {

    private let modelName: String

    init(modelName: String) {
        self.modelName = modelName
    }

    private lazy var storeContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: self.modelName)
        container.loadPersistentStores {
            (storeDescription, error) in
            if let error = error as NSError? {
                print("Unresolved error \(error), \(error.userInfo)")
            }
        }
        return container
    }()

    lazy var managedContext: NSManagedObjectContext = {
        return self.storeContainer.viewContext
    }()

    func saveContext() {
        guard managedContext.hasChanges else { return }
        do {
            try managedContext.save()
        } catch let error as NSError {
            print("Unresolved error \(error), \(error.userInfo)")
        }
    }
}

1.2 ViewController

import CoreData

然后添加属性

var managedContext: NSManagedObjectContext!

1.3 AppDelegate

lazy var coreDataStack = CoreDataStack(modelName: "UserRecords")

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    
    // CoreData
    guard let navController = window?.rootViewController as? UINavigationController,
    let viewController = navController.topViewController as? MainViewController else { // MainViewController是导航视图指向的第一个控制器
        return true
    }
    viewController.managedContext = coreDataStack.managedContext
    return true
}

2 数据建模

File\New\File..., 选 iOS\Core Data\Data Model template Name the file 库名.xcdatamodeld。

Codegen最好改成Manual 要不然可能有redeclaration报错

3 添加managed object subclass

** Editor\Create NSManagedObject Subclass...** 选刚刚添加的Entity名字，一般默认一直继续下去就可以了。