我正在开发一个硬币收集应用程序，最近我开始将核心数据集成到我的应用程序中。我有一个存储自定义 CoinCategory 对象的核心数据数据库，每个 CoinCategory 对象都有一个 Coin 对象数组。这样，我的应用程序就可以按类别存储所有内容。
当我集成核心数据时，我可以毫无错误地添加我的第一个类别，也可以毫无问题地删除它，但是当我添加第二个硬币类别时，我遇到以下错误:
2017-06-26 09:55:37.218 CoinCollection[18889:12839563] -[CoinCollection.CoinCategory 比较:]:无法识别的选择器发送到实例 0x608000236cc0
2017-06-26 09:55:37.219215-0400 CoinCollection[18889:12839563] [错误] 错误:严重的应用程序错误。在核心数据更改处理期间捕获到异常。这通常是 NSManagedObjectContextObjectsDidChangeNotification 观察者中的错误。 -[CoinCollection.CoinCategory 比较:]:无法识别的选择器发送到带有 userInfo 的实例 0x608000236cc0(空)
CoreData:错误:严重的应用程序错误。在核心数据更改处理期间捕获到异常。这通常是 NSManagedObjectContextObjectsDidChangeNotification 观察者中的错误。 -[CoinCollection.CoinCategory compare:]: 无法识别的选择器发送到实例 0x608000236cc0 with userInfo (null)
谁能告诉我如何解决这个问题？非常感谢!
我在下面附上我的代码，用于我的 View Controller 和运行核心数据的应用程序委托(delegate)。
AppDelegate.swift
// We customize the app, system-wide
import UIKit
import CoreData
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
// MARK: - Core Data stack
lazy var persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "CoinCollection")
container.loadPersistentStores(completionHandler: { (storeDescription,
error) in
if let error = error as NSError? {
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
return container
}()
// MARK: - Core Data Saving support
func saveContext ()
{
let context = persistentContainer.viewContext
if context.hasChanges
{
do
{
try context.save()
}
catch
{
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate.
//You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}
}
然后是我的 View Controller 。请注意，我从调用此方法的 subview Controller 中获取了一个 Coin 对象，并且我们决定该 Coin 对象是否适合现有类别。如果没有，那么我们添加新的硬币。
// Controls the table view controller showing the general coins (one per each category)
import UIKit
import CoreData
class CoinTableViewController: UITableViewController, NSFetchedResultsControllerDelegate {
//this is an array of all the coins in the collection
//each row of this two-dimensional array represents a new category
var coinsByCategory: [CoinCategoryMO] = []
var fetchResultController: NSFetchedResultsController<CoinCategoryMO>!
//other attributes....
////////////////////////////////////////////////////////////////////////
override func viewDidLoad()
{
super.viewDidLoad()
//////////////////////////////////////////////////////////////////////////////////
//we now fetch the data
let fetchRequest : NSFetchRequest<CoinCategoryMO> = CoinCategoryMO.fetchRequest()
if let appDelegate = (UIApplication.shared.delegate as? AppDelegate)
{
let context = appDelegate.persistentContainer.viewContext
let sortDescriptor = NSSortDescriptor(key: "coinCategory", ascending: true)
fetchRequest.sortDescriptors = [sortDescriptor]
fetchResultController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
fetchResultController.delegate = self
do
{
try fetchResultController.performFetch()
if let fetchedObjects = fetchResultController.fetchedObjects
{
self.coinsByCategory = fetchedObjects
}
}
catch
{
print(error)
}
}
//configure even more....
}
// MARK: - Table view data soure
func deleteCoinCategory(rowPath: IndexPath)
{
if 0 <= rowPath.row && rowPath.row < self.coinsByCategory.count
{
//we have just tested that the rowPath index is valid
if let appDelegate = (UIApplication.shared.delegate as? AppDelegate)
{
let context = appDelegate.persistentContainer.viewContext
let coinCategoryToDelete = self.fetchResultController.object(at: rowPath)
context.delete(coinCategoryToDelete)
appDelegate.saveContext()
}
}
}
func deleteCoin(c: Coin, indexOfSelectedCategory: IndexPath) -> Bool
{
//we have a coin that we want to delete from this viewcontroller
//and the data contained in it.
//
//the parameter indexOfSelectedCategory refers to the IndexPath of the
//row in the TableView contained in THIS viewcontroller whose category
//of coins we are modifying in this method
//
//Return value: a boolean that indicates whether a single coin has
//been deleted - meaning that the user should return to the parentviewcontroller
if 0 < indexOfSelectedCategory.row && indexOfSelectedCategory.row < self.coinsByCategory.count && self.coinsByCategory[indexOfSelectedCategory.row].coinCategory?.hasCoin(c: c) == true
{
//the index is valid as it refers to a category in the coinsByCategory array
//and the examined category has the coin in question
if self.coinsByCategory[indexOfSelectedCategory.row].coinCategory?.count == 1
{
//the coin "c" that we are going to delete is the only coin in the entire category
self.deleteCoinCategory(rowPath: indexOfSelectedCategory)
return true
}
else
{
//more than one coin in the category
self.coinsByCategory[indexOfSelectedCategory.row].coinCategory?.removeCoin(c: c)
//we save the changes in the database...
if let appDelegate = (UIApplication.shared.delegate as? AppDelegate)
{
appDelegate.saveContext()
}
return false
}
}
return false
}
func addCoin(coinToAdd: Coin)
{
//we check over each category to see if the coin can be added
for category in self.coinsByCategory
{
if category.coinCategory?.coinFitsCategory(aCoin: coinToAdd) == true
{
//we can add the coin to the category
category.coinCategory?.addCoin(newCoin: coinToAdd)
if let appDelegate = (UIApplication.shared.delegate as? AppDelegate)
{
//we save changes to the database
appDelegate.saveContext()
//we are DONE with this function
return
}
}
}
//since the coinToAdd does not fall in the existing categories, we create a new one
if let appDelegate = (UIApplication.shared.delegate as? AppDelegate)
{
let newCategory = CoinCategoryMO(context: appDelegate.persistentContainer.viewContext)
newCategory.coinCategory = CoinCategory(coins: [coinToAdd], categoryType: CoinCategory.CategoryTypes.COUNTRY_VALUE_AND_CURRENCY)
print("Saving data to context ...")
appDelegate.saveContext()
}
}
//delegate methods control the core data database
func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>)
{
tableView.beginUpdates()
}
func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?)
{
switch type
{
case .insert :
if let newIndexPath = newIndexPath
{
tableView.insertRows(at: [newIndexPath], with: .fade)
}
case .delete:
if let indexPath = indexPath
{
tableView.deleteRows(at: [indexPath], with: .fade)
}
case .update:
if let indexPath = indexPath
{
tableView.reloadRows(at: [indexPath], with: .fade)
}
default:
tableView.reloadData()
}
if let fetchedObjects = controller.fetchedObjects
{
self.coinsByCategory = fetchedObjects as! [CoinCategoryMO]
}
}
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>)
{
tableView.endUpdates()
}
我期待听到您的想法，并提前感谢您的帮助!
编辑:
我的 CoinCategory 类代码:
// This class is supposed to represent a category of coin objects in CoreData
import Foundation
import CoreData
public class CoinCategory: NSObject, NSCoding
{
//These are the various types of categories that a user can create out of their coin collection
enum CategoryTypes : NSString
{
case COUNTRY_VALUE_AND_CURRENCY = //...
case COUNTRY = //...
case YEAR = //...
case CURRENCY = //...
case NO_CATEGORY = //...
}
//this struct is used to encode data in Key-Value pairs per the NSCoding protocol
struct Keys
{
static let Current_Category_Type = "current_category_type"
static let Coins_In_Category = "coins_in_category"
}
//this is the collection of the coins in the category
var coinsInCategory: [Coin] = [] //initially we have no coins in the collection
var currentCategoryType : CategoryTypes.RawValue = ""
public var count : NSNumber
{
get
{
//..number of coins in category
}
}
public var array : [Coin]
{
get
{
//read-only copy of the Coins array..
}
}
public required init?(coder aDecoder: NSCoder)
{
//we decode this object's information
if let categoryTypeObject = aDecoder.decodeObject(forKey: Keys.Current_Category_Type) as? CategoryTypes.RawValue
{
self.currentCategoryType = categoryTypeObject
}
if let coinsInCategoryArrayObject = aDecoder.decodeObject(forKey: Keys.Coins_In_Category) as? [Coin]
{
self.coinsInCategory = coinsInCategoryArrayObject
}
}
public func encode(with aCoder: NSCoder)
{
//we encode this object's information
aCoder.encode(currentCategoryType, forKey: Keys.Current_Category_Type)
aCoder.encode(self.coinsInCategory, forKey: Keys.Coins_In_Category)
}
override init()
{
super.init()
self.currentCategoryType = CategoryTypes.COUNTRY_VALUE_AND_CURRENCY.rawValue
self.coinsInCategory = []
}
convenience init(coins: [Coin], categoryType: CategoryTypes.RawValue)
{
self.init()
self.coinsInCategory = coins
if isACategoryType(categoryType: categoryType) == true
{
self.currentCategoryType = categoryType
}
else
{
self.currentCategoryType = CategoryTypes.NO_CATEGORY.rawValue
}
}
func isACategoryType(categoryType: NSString) -> Bool
{
switch categoryType
{
case CategoryTypes.COUNTRY_VALUE_AND_CURRENCY.rawValue:
return true
case CategoryTypes.COUNTRY.rawValue:
return true
case CategoryTypes.YEAR.rawValue:
return true
case CategoryTypes.CURRENCY.rawValue:
return true
default:
return false
}
}
func addCoin(newCoin: Coin)
{
//we are adding a new Coin object to this category
//if it falls into the category's type
if self.coinFitsCategory(aCoin: newCoin) == true
{
self.coinsInCategory.append(newCoin)
}
}
func coinFitsCategory(aCoin: Coin) -> Bool
{
//this function tests if aCoin fits into the category type
//but that all varies depending on which category the coin is
if self.coinsInCategory.count == 0
{
//this category is currently empty, so any addition goes!
return true
}
//otherwise, this category is not empty... so we are now going to
//examine the situation more critically
let testCoin = self.coinsInCategory[0]
switch self.currentCategoryType
{
case CategoryTypes.COUNTRY_VALUE_AND_CURRENCY.rawValue:
return (testCoin.getCountry().lowercased == aCoin.getCountry().lowercased) && (testCoin.getValue() == aCoin.getValue()) && (testCoin.getDenomination().lowercased == aCoin.getDenomination().lowercased)
case CategoryTypes.COUNTRY.rawValue:
return testCoin.getCountry().lowercased == aCoin.getCountry().lowercased
case CategoryTypes.CURRENCY.rawValue:
return testCoin.getDenomination().lowercased == aCoin.getDenomination().lowercased
case CategoryTypes.YEAR.rawValue:
return testCoin.getYear() == aCoin.getYear()
default:
return false
}
}
func getIndexOfCoinInCollection(coin: Coin) -> Int
{
//we are going to return -1 if the coin does not exist in the collection
//and are going to return the index otherwise if yes
for i in 0..<self.coinsInCategory.count
{
if coinsInCategory[i] == coin
{
return i
}
}
//have not found anything
return -1
}
func removeCoin(at: Int)
{
//we remove the coin at the index if it is in a valid range of the coinInCategory array
if isValidArrayIndex(index: at)
{
self.coinsInCategory.remove(at: at)
}
}
func getCoin(at: Int) -> Coin?
{
//we return nil if there is an issue in accessing the coin
if isValidArrayIndex(index: at)
{
return self.coinsInCategory[at]
}
else
{
return nil
}
}
func assignCoin(at: Int,c: Coin)
{
if isValidArrayIndex(index: at)
{
self.coinsInCategory[at].assign(right: c)
}
}
func deleteAllCoins()
{
//we delete all the coin in this category
self.coinsInCategory.removeAll()
}
func removeCoin(c: Coin)
{
//we delete a coin from the category
for i in 0..<self.coinsInCategory.count
{
if self.coinsInCategory[i] == c
{
//the coin at index "i" is equal to the coin "c" that we want to delete from the category
self.coinsInCategory.remove(at: i)
return
}
}
}
func hasCoin(c: Coin) -> Bool
{
return getIndexOfCoinInCollection(coin: c) != -1
}
func swapValuesWithAnotherCategory(other: CoinCategory)
{
swap(&self.currentCategoryType, &other.currentCategoryType)
swap(&self.coinsInCategory,&other.coinsInCategory)
}
func swapCoins(indexOne: Int, indexTwo: Int)
{
if isValidArrayIndex(index: indexOne) && isValidArrayIndex(index: indexTwo)
{
swap(&self.coinsInCategory[indexOne],&self.coinsInCategory[indexTwo])
}
}
private func isValidArrayIndex(index: Int) -> Bool
{
return (0 <= index && index < coinsInCategory.count)
}
}
然后是硬币类别类: //这里为项目提供了Class Coin的类定义
import UIKit
import CoreData
enum TimePeriods: String
{
//this enumeration represents the different time periods that a
//coin was minted in, for the sake of this programn
case BCE = "BCE"
case CE = "CE"
}
public class Coin : NSObject, NSCoding
{
//this struct represents all the keys used in encoding and decoding this object
struct Keys
{
static let Country = "country"
static let Mint = "mint"
static let Year = "year"
static let Currency = "currency"
static let Value = "value"
static let Grade = "grade"
static let Comments = "comments"
static let NumInstances = "numberInstances"
static let Description = "description"
static let Obverse = "obverse"
static let Reverse = "reverse"
}
//this represents a coin in the table view
static let GRADING_LOWER_LIMIT: NSNumber = 1
static let GRADING_UPPER_LIMIT: NSNumber = 70
//this represents the default strings returned if a field does not have the needed information
static let DEFAULT_DESCRIPTIVE_NAME: NSString = "(Description?)"
static let DEFAULT_COMMENTS: NSString = "(Comments?)"
static let DEFAULT_DENOMINATION: NSString = "(Denomination?)"
static let DEFAULT_MINT: NSString = "(Mint?)"
static let DEFAULT_COUNTRY: NSString = "(Country?)"
static let DEFAULT_YEAR: NSString = "(Year?)"
static let DEFAULT_GRADE: NSString = "(Grade?)"
static let DEFAULT_VALUE_AND_DENOMINATION: NSString = "(Value?) (Currency?)"
static let OBVERSE_IMAGE_STRING : NSString = "Obverse"
static let REVERSE_IMAGE_STRING : NSString = "Reverse"
static private let BULLET = "➣ " //represents the kind of bullet to be used to build a complete summary of the coin
//declare members with setters and getters
private var country: NSString = "" //what country/empire/etc. used in?
private var mint: NSString = "" //where minted? EX: US Mint, St. Petersburg
private var year: NSNumber? = nil //what year minted? per gregorian calendar
//the year can be negative to represent the BCE period
//positive to represent the CE periods
private var typeCurrency: NSString = "" //what is the unit of value? EX: Cents, dollars, centavos, etc
private var theValue: NSNumber = 0 //how many? EX: how many dollars, cents, centavos, etc.?
//additional information about the coin
private var grade: NSNumber? //on the american grading scale for coins. 1-70
private var comments: NSString = "" //extra comments stored by the user for himself
private var numberOfInstances: NSNumber = 0 //number of coins exactly like this. EX: 1,2,3,4...etc? For each instance, it must be >= 1.
//This describes the type of the coin
//EX: Walking Liberty Quarter, Barber Quarter, Standing Liberty Quarter... etc
private var descriptiveName: NSString = ""
private var obverseImage: UIImage? = nil
private var reverseImage: UIImage? = nil
public var valueAndDenomination: NSString
{
get
{
//need to check four cases
//case 1: we have the right values for value and denomination
//case 2: we do not have a value but do have denomination
//case 3: we have a value but do not have denomination
//case 4: we do not have both
//
//the reason why we consider 0 to be an empty value is because a coin that was worth
//nothing would not have been minted in the first place!!!
if (self.theValue != 0 && self.typeCurrency != "")
{
//have value and denomination
return "\(self.theValue) \(self.typeCurrency)" as NSString //like "20 Cents"
}
else if (self.theValue == 0 && self.typeCurrency != "" )
{
//do not have value, but have denomination
return "(Value?) \(self.typeCurrency)" as NSString
}
else if (self.theValue != 0 && self.typeCurrency == "")
{
//we have value, but do not have denomination
return "\(self.theValue) (Currency?)" as NSString
}
else
{
//we do not have both
return Coin.DEFAULT_VALUE_AND_DENOMINATION as NSString
}
}
}
public required init?(coder aDecoder: NSCoder)
{
//we decode this object's information
if let countryObject = aDecoder.decodeObject(forKey: Keys.Country) as? NSString
{
self.country = countryObject
}
if let mintObject = aDecoder.decodeObject(forKey: Keys.Country) as? NSString
{
self.mint = mintObject
}
if let yearObject = aDecoder.decodeObject(forKey: Keys.Year) as? NSNumber
{
self.year = yearObject
}
if let currencyObject = aDecoder.decodeObject(forKey: Keys.Currency) as? NSString
{
self.typeCurrency = currencyObject
}
if let valueObject = aDecoder.decodeObject(forKey: Keys.Value) as? NSNumber
{
self.theValue = valueObject
}
if let gradeObject = aDecoder.decodeObject(forKey: Keys.Grade) as? NSNumber
{
self.grade = gradeObject
}
if let commentObject = aDecoder.decodeObject(forKey: Keys.Comments) as? NSString
{
self.comments = commentObject
}
if let numInstancesObject = aDecoder.decodeObject(forKey: Keys.NumInstances) as? NSNumber
{
self.numberOfInstances = numInstancesObject
}
if let descriptiveNameObject = aDecoder.decodeObject(forKey: Keys.Description) as? NSString
{
self.descriptiveName = descriptiveNameObject
}
if let obverseImageObject = aDecoder.decodeObject(forKey: Keys.Obverse) as? UIImage
{
self.obverseImage = obverseImageObject
}
if let reverseImageObject = aDecoder.decodeObject(forKey: Keys.Reverse) as? UIImage
{
self.reverseImage = reverseImageObject
}
}
override init()
{
//default initializer
super.init()
self.country = ""
self.mint = ""
self.year = nil
self.typeCurrency = ""
self.theValue = 0
self.comments = ""
self.numberOfInstances = 1
self.descriptiveName = ""
self.obverseImage = nil
self.reverseImage = nil
}
init(country: NSString,year: Int?,typeCurrency: NSString, theValue: NSNumber,mint: NSString,grade: Int?,numInstances: NSNumber = 1,description: NSString, comments: NSString)
{
super.init()
self.country = country
self.mint = mint
self.year = year! as NSNumber
self.typeCurrency = typeCurrency
self.theValue = theValue
self.comments = comments
self.numberOfInstances = numInstances
self.descriptiveName = description
self.obverseImage = nil
self.reverseImage = nil
}
init(country: NSString,year: NSNumber?,typeCurrency: NSString, theValue: NSNumber,mint: NSString,grade: NSNumber?,numInstances: NSNumber = 1,description: NSString, comments: NSString,obverseImage: UIImage, reverseImage: UIImage)
{
super.init()
self.country = country
self.mint = mint
self.year = year
self.typeCurrency = typeCurrency
self.theValue = theValue
self.comments = comments
self.numberOfInstances = numInstances
self.descriptiveName = description
}
public func encode(with aCoder: NSCoder)
{
//we encode the coin's information
aCoder.encode(self.country, forKey: Keys.Country)
aCoder.encode(self.mint, forKey: Keys.Mint)
aCoder.encode(self.year, forKey: Keys.Year)
aCoder.encode(self.typeCurrency, forKey: Keys.Currency)
aCoder.encode(self.theValue, forKey: Keys.Value)
aCoder.encode(self.grade, forKey: Keys.Grade)
aCoder.encode(self.comments, forKey: Keys.Comments)
aCoder.encode(self.numberOfInstances, forKey: Keys.NumInstances)
aCoder.encode(self.descriptiveName, forKey: Keys.Description)
aCoder.encode(self.obverseImage, forKey: Keys.Obverse)
aCoder.encode(self.reverseImage, forKey: Keys.Reverse)
}
//setter and getter functions for class members...
func getCompleteSummary() -> NSString
{
//returns a bulleted list that represents the coin
//and it describes every single detail...
}
func getIncompleteSummary() -> String
{
//returns a bulleted list string that represents the coin
//and it describes every single detail...
}
/////////////////////////////////////////////////////////////////////////////////
func ofSameType(rhs: Coin) -> Bool
{
return (self.getCountry().lowercased == rhs.getCountry().lowercased) && (self.getValue() == rhs.getValue()) && (self.getDenomination().lowercased == rhs.getDenomination().lowercased)
}
public static func==(lhs: Coin, rhs: Coin) -> Bool
{
//we compare two coin objects for equality in ALL Categories
return lhs.country.lowercased == rhs.country.lowercased &&
lhs.theValue == rhs.theValue &&
lhs.typeCurrency.lowercased == rhs.typeCurrency.lowercased &&
lhs.mint.lowercased == rhs.mint.lowercased &&
lhs.year == rhs.year &&
lhs.grade == rhs.grade &&
lhs.comments == rhs.comments &&
lhs.numberOfInstances == rhs.numberOfInstances &&
lhs.descriptiveName == rhs.descriptiveName &&
lhs.obverseImage == rhs.obverseImage &&
lhs.reverseImage == rhs.reverseImage
}
func assign(right: Coin)
{
//we implement this instead of overloading the assignment "=" operator
//as it is not possible to overload the "=" operator
//we assign the right-hand-coin's field values
//to the left-hand coin's side
self.country = right.country
self.theValue = right.theValue
self.typeCurrency = right.typeCurrency
self.mint = right.mint
self.year = right.year
self.grade = right.grade
self.comments = right.comments
self.numberOfInstances = right.numberOfInstances
self.descriptiveName = right.descriptiveName
self.obverseImage = right.obverseImage
self.reverseImage = right.reverseImage
}
}
最佳答案
看起来问题是您的 CoinCategory 类没有实现 compare: 方法:
[CoinCollection.CoinCategory compare:]: unrecognized selector sent to instance 0x608000236cc0
我的猜测是 FRC 正在尝试将第二个 CoinCategoryMO 的 coinCategory 属性与第一个 的 以便以正确的顺序获取它们(因为您的 FRC 是使用 coinCategory 属性进行比较>CoinCategoryMOcoinCategory 属性排序的)。
所以直接的答案是您需要为您的CoinCategory 类实现一个compare: 方法。但我认为这只是一个指标，表明你需要改变你的方法。与其拥有一个具有自定义对象(或其集合)属性的实体，不如拥有多个实体(例如，一个 CoinMO 实体，一个 CoinCategoryMO 实体， CoinCategoryTypeMO 实体等)，它们之间存在一对多关系。如果您显示自定义对象(Coin 和 CoinCategory)的代码，那么建议如何最好地在 CoreData 中建模它们会更容易。
关于ios - 核心数据更改处理时出错，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44762356/