CoreData Swift:如何保存和加载数据？

Question

我正在Swift中编写一个iOS游戏,我想在最后添加一个高分标签.我认为保存功能是正确的,但负载一是给我带来问题的.我已经创建了一个实体("BestScores")和属性("classicBestScoreTF"):

要保存高分:

var bestscore25 = 1000
var score: int

func savescore() {    
    var appDel: AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    var context:NSManagedObjectContext = appDel.managedObjectContext!
    var score25: AnyObject! = NSEntityDescription.insertNewObjectForEntityForName("BestScores", inManagedObjectContext: context) as NSManagedObject
    score25.setValue(score, forKey: "classicBestScoreTF")
    context.save(nil)
}

func loadscore() {
    var appDel: AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
    var context:NSManagedObjectContext = appDel.managedObjectContext!
    bestScore25 = valueForKey("classicBestScoreTF") as Int
}

func endgame() {

    if score > bestScore25 {
        savescore()
        loadscore()
        bestScoreLabel.text = "Best Score: \(bestScore25)"
    }

    if score < bestscore {            
        loadscore()
        bestScoreLabel.text = "Best Score: \(bestScore25)"
    }    
}

它不工作:(请帮忙!

Answer 1

保存数据:

var person = NSEntityDescription.insertNewObjectForEntityForName("Person", 
inManagedObjectContext: self.managedObjectContext!) as Person
person.name = "Mary"
person.age = Float(arc4random() % 100)

var error : NSError? = nil
if !self.managedObjectContext!.save(&error) {
    NSLog("Unresolved error \(error), \(error!.userInfo)")
    abort()
}

加载数据中:

var error: NSError? = nil
var fReq: NSFetchRequest = NSFetchRequest(entityName: "Frases")    
fReq.predicate = NSPredicate(format: "id contains[c] %@", String(day))
var sorter: NSSortDescriptor = NSSortDescriptor(key: "id" , ascending: false)
fReq.sortDescriptors = [sorter]
fReq.returnsObjectsAsFaults = false
let result : [AnyObject] = self.managedObjectContext!.executeFetchRequest(fReq, error:&error)!

Answer 2

斯威夫特 5

步骤 1. 使用 CoreData 选项创建简单的应用程序

步骤 2. 打开.xcdatamodeld文件并以这种方式添加Entity , Attributes

步骤 3. 你的 AppDelegate 应该有Core Data 堆栈方法

步骤 4. 确保你有如下的 swift code snipe

import UIKit
import CoreData

class ViewController: UIViewController {

    // MARK: Variables declearations
    let appDelegate = UIApplication.shared.delegate as! AppDelegate //Singlton instance
    var context:NSManagedObjectContext!

    // MARK: View Controller life cycle methods
    override func viewDidLoad() {
        super.viewDidLoad()

        openDatabse()
    }

    // MARK: Methods to Open, Store and Fetch data
    func openDatabse()
    {
        context = appDelegate.persistentContainer.viewContext
        let entity = NSEntityDescription.entity(forEntityName: "Users", in: context)
        let newUser = NSManagedObject(entity: entity!, insertInto: context)
        saveData(UserDBObj:newUser)
    }

    func saveData(UserDBObj:NSManagedObject)
    {
        UserDBObj.setValue("RDC", forKey: "username")
        UserDBObj.setValue("1234", forKey: "password")
        UserDBObj.setValue("21", forKey: "age")

        print("Storing Data..")
        do {
            try context.save()
        } catch {
            print("Storing data Failed")
        }

        fetchData()
    }

    func fetchData()
    {
        print("Fetching Data..")
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
        request.returnsObjectsAsFaults = false
        do {
            let result = try context.fetch(request)
            for data in result as! [NSManagedObject] {
                let userName = data.value(forKey: "username") as! String
                let age = data.value(forKey: "age") as! String
                print("User Name is : "+userName+" and Age is : "+age)
            }
        } catch {
            print("Fetching data Failed")
        }
    }
}

步骤 5. 在设备上运行并查看核心数据结果的日志