Swift

Question

我在 Swift 中遇到以下情况：

我有一个名为 Event 的 NSManaged class：

import UIKit
import Foundation
import CoreData

class Event: NSManagedObject, NSCoding {

@NSManaged var eventArchived: Bool
@NSManaged var eventCCRecipientAddress: String?
@NSManaged var eventCCRecipientName: String?
@NSManaged var eventEndDate: String?
@NSManaged var eventEndRSVPDateTime: String?
@NSManaged var eventHappeningId: String?
@NSManaged var eventName: String?
@NSManaged var eventResourcesFolderName: String?
@NSManaged var eventStartDate: String?
@NSManaged var eventId: String?
@NSManaged var eventHappening: Happening

override init(entity: NSEntityDescription, insertIntoManagedObjectContext context: NSManagedObjectContext?) {
    super.init(entity: entity, insertIntoManagedObjectContext: context)
}

// MARK: NSCoding protocol conformance
required init(coder aDecoder: NSCoder) {

    let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext!
    let entity = NSEntityDescription.entityForName("Event", inManagedObjectContext: context)!

    // Note: pass `nil` to `insertIntoManagedObjectContext`
    super.init(entity: entity, insertIntoManagedObjectContext: nil)

    if let eventArchived = aDecoder.decodeObjectForKey("eventArchived") as? Bool {
        self.eventArchived = eventArchived
    }
    if let eventCCRecipientAddress = aDecoder.decodeObjectForKey("eventCCRecipientAddress") as? String {
        self.eventCCRecipientAddress = eventCCRecipientAddress
    }
    if let eventCCRecipientName = aDecoder.decodeObjectForKey("eventCCRecipientName") as? String {
        self.eventCCRecipientName = eventCCRecipientName
    }
    if let eventEndDate = aDecoder.decodeObjectForKey("eventEndDate") as? String {
        self.eventEndDate = eventEndDate
    }
    if let eventEndRSVPDateTime = aDecoder.decodeObjectForKey("eventEndRSVPDateTime") as? String {
        self.eventEndRSVPDateTime = eventEndRSVPDateTime
    }
    if let eventHappeningId = aDecoder.decodeObjectForKey("eventHappeningId") as? String {
        self.eventHappeningId = eventHappeningId
    }
    if let eventName = aDecoder.decodeObjectForKey("eventName") as? String {
        self.eventName = eventName
    }
    if let eventResourcesFolderName = aDecoder.decodeObjectForKey("eventResourcesFolderName") as? String {
        self.eventResourcesFolderName = eventResourcesFolderName
    }
    if let eventStartDate = aDecoder.decodeObjectForKey("eventStartDate") as? String {
        self.eventStartDate = eventStartDate
    }
    if let eventId = aDecoder.decodeObjectForKey("eventId") as? String {
        self.eventId = eventId
    }
}

func encodeWithCoder(aCoder: NSCoder) {

    aCoder.encodeObject(eventArchived, forKey: "eventArchived")

    if let eventCCRecipientAddress = self.eventCCRecipientAddress {
        aCoder.encodeObject(eventCCRecipientAddress, forKey: "eventCCRecipientAddress")
    }
    if let eventCCRecipientName = self.eventCCRecipientName {
        aCoder.encodeObject(eventCCRecipientName, forKey: "eventCCRecipientName")
    }
    if let eventEndDate = self.eventEndDate {
        aCoder.encodeObject(eventEndDate, forKey: "eventEndDate")
    }
    if let eventEndRSVPDateTime = self.eventEndRSVPDateTime {
        aCoder.encodeObject(eventEndRSVPDateTime, forKey: "eventEndRSVPDateTime")
    }
    if let eventCCRecipientAddress = self.eventCCRecipientAddress {
        aCoder.encodeObject(eventCCRecipientAddress, forKey: "eventCCRecipientAddress")
    }
    if let eventHappeningId = self.eventHappeningId {
        aCoder.encodeObject(eventHappeningId, forKey: "eventHappeningId")
    }
    if let eventName = self.eventName {
        aCoder.encodeObject(eventName, forKey: "eventName")
    }
    if let eventResourcesFolderName = self.eventResourcesFolderName {
        aCoder.encodeObject(eventResourcesFolderName, forKey: "eventResourcesFolderName")
    }
    if let eventStartDate = self.eventStartDate {
        aCoder.encodeObject(eventStartDate, forKey: "eventStartDate")
    }
    if let eventId = self.eventId {
        aCoder.encodeObject(eventId, forKey: "eventId")
    }

    aCoder.encodeObject(eventHappening, forKey: "eventHappening")
}
}

class 曾经是 "simple" 只有 NSManaged 变量，直到我被要求实现 NSCoding 协议。我使用 NSCoding 是因为我需要在我的应用程序的任何地方了解当前事件，包括离线模式。

当我尝试使用我的事件 Class 时，我一直出现以下错误：

CoreData: error: Failed to call designated initializer on NSManagedObject class 'AccueilInviteVIP.Event'

这就是我尝试访问我的 class 的方式：

var currentEvent = Event()

然后在viewDidLoad方法中：

    // currentEvent
    currentEvent = NSEntityDescription.insertNewObjectForEntityForName("Event", inManagedObjectContext: self.managedObjectContext!) as! Event

它在这条线上崩溃了。

错误应该很清楚，似乎我的 init 方法不正确但我无法让它工作，因为我是 Swift 的新手并且找不到任何接近此的示例。

任何帮助都会很棒！

谢谢，

雨果

Answer 1

对我来说，这看起来像是过度工程化和太多的代码。

为什么不只存储 eventId 并从核心数据中检索对象？还要归档它看起来真的很乱和多余。

// store
NSUserDefaults.standardUserDefaults().setObject(event.eventId forKey:"mainEventID")

// retrieve
let eventId = NSUserDefaults.standardUserDefaults().stringForKey("mainEventId")!
let request = NSFetchRequest(entityName: "Event")
request.predicate = NSPredicate(format: "eventId = %@", eventId)
let event = (context.executeFetchRequest(request, error:nil) as [Event]).first!

您将不得不做更多的错误并 nil 检查，但您明白了。

Swift - 核心数据和 NSCoding：无法调用指定的初始化程序

Swift - Core Data & NSCoding : Failed to call designated initializer

core-data

nscoding

ios