Question

我在Swift中遇到以下案例：

我有一个名为Event：

的NSManaged类

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")
}
}

以前的班级很简单＆＃34;在我被要求实施NSCoding协议之前，只有NSManaged变量。我使用NSCoding是因为我需要知道我的应用程序中的当前事件，包括离线模式。

当我尝试使用我的事件类时，我一直有以下错误：

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

这是我尝试访问我的课程的方式：

var currentEvent = Event()

然后在viewDidLoad方法中：

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

它就崩溃了。

错误应该非常清楚，似乎我的init方法不正确，但我无法让它工作，因为我是Swift的新手并且无法找到任何接近此的示例。

任何帮助都会很棒！

谢谢，

雨果

Answer 1

看起来像过度工程和太多的代码给我。

为什么不直接存储eventId并从Core Data中检索对象？为了归档它看起来非常混乱和多余。

// 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!

你必须做更多的错误和nil检查，但你明白了。

Swift - 核心数据＆amp; NSCoding：无法调用指定的初始化程序

1 个答案: