Question

我尝试在我的应用中实现核心数据。我可以在模拟器中插入数据和获取数据。我尝试打印数据，数据存在。但是当我打开sqlite文件时，数据是空的。它只有表和属性但没有数据。我使用swift 3。

这是JobOrder.swift

import Foundation
import CoreData

public class JobOrder: NSManagedObject {

}

这是JobOrder + CoreDataProperties.swift

import Foundation
import CoreData

extension JobOrder {

@nonobjc public class func fetchRequest() -> NSFetchRequest<JobOrder> {
    return NSFetchRequest<JobOrder>(entityName: "JobOrder");
}

@NSManaged public var body: String?
@NSManaged public var id: Int64
@NSManaged public var orderID: Int64

 }

这是我插入数据的方式

 func seedPerson(){

    let entity = NSEntityDescription.insertNewObject(forEntityName: "JobOrder", into: moc)

    entity.setValue("name", forKey: "body")

    do{
        try moc.save()
    }catch{
        fatalError("failed: \(error)")
    }
}

这是我获取数据的方式

func fetch(){
    let personFetch = NSFetchRequest<NSFetchRequestResult>(entityName: "JobOrder")
    do{
        let fetchPerson = try moc.fetch(personFetch)
        print("bodyName \((fetchPerson.first! as AnyObject).body!))")
    }
    catch {
    }
}

对于insert和fetch，它工作但是当打开我的sqlite文件时，数据不存在。

这是我的文件DataController

import UIKit
import CoreData
class DataController: NSObject {
var managedObjectContext: NSManagedObjectContext
override init() {
    // This resource is the same name as your xcdatamodeld contained in your project.
    guard let modelURL = Bundle.main.url(forResource: "modeldb", withExtension:"momd") else {
        fatalError("Error loading model from bundle")
    }
    // The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
    guard let mom = NSManagedObjectModel(contentsOf: modelURL) else {
        fatalError("Error initializing mom from: \(modelURL)")
    }
    let psc = NSPersistentStoreCoordinator(managedObjectModel: mom)
    managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
    managedObjectContext.persistentStoreCoordinator = psc

        let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        let docURL = urls[urls.endIndex-1]

        //          let storeURL = docURL.URLByAppendingPathComponent("modeldb.sqlite")
        let storeURL = NSURL(string:"modeldb.sqlite", relativeTo:docURL)
        do {
            try psc.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeURL as URL?, options: nil)
        } catch {
            fatalError("Error migrating store: \(error)")
        }
    }
}

我在日志中也有错误

CoreData: warning: Unable to load class named 'JobOrder' for entity 'JobOrder'.  Class not found, using default NSManagedObject instead.

Answer 1

进一步的讨论导致了一个关于如何使用Swift 3.0关闭CoreData中的WAL模式的问题。所以我在这里添加必要的代码作为答案，以便其他人也可以从中受益：

let dict = [NSSQLitePragmasOption: ["journal_mode":"DELETE"]]
do {
    try coordinator.addPersistentStore(ofType:NSSQLiteStoreType, configurationName:nil, at:url, options:dict)
} catch {
    // Report error
    abort()
}

在上文中，coordinator是NSPersistentStoreCoordinator实例，url是指向持久存储位置的URL实例。

Sqlite文件为空，但数据可以使用核心数据在模拟器中获取视图

1 个答案: