本文介绍了可编码的NSManagedObject失败,原因为ifcodeIfPresent数据类型的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我尝试解码此json时收到此错误:
I obtain this error when i'm trying to decode this json:
[{
"id": "76f22c25-cee7-4c7a-94fa-1fb85720f580",
"purchaseDate": "2012-04-05T19:03:43Z",
"title": "azare",
}, {
"id": "9b4b9f7d-382f-4555-9eaa-97939b13633f",
"purchaseDate": "2012-04-05T19:02:46Z",
"title": "Chocolat",
}, {
"id": "02a0aa06-2d0c-4ab9-aaaa-af7dee7b4845",
"purchaseDate": "2012-09-24T17:39:52Z",
"title": "Some thing",
}]
My code:
//Purchase+CoreDataClass.swift
@objc(Purchase)
public class Purchase: NSManagedObject, Codable {
enum CodingKeys: String, CodingKey {
case id
case title
case purchaseDate
}
required convenience public init(from decoder: Decoder) throws {
var context : NSManagedObjectContext = MyAppCoreDataManager.sharedInstance.persistentContainer.viewContext
guard let entity = NSEntityDescription.entity(forEntityName: "Purchase", in: context!) else { fatalError() }
self.init(entity: entity, insertInto: context!)
let container = try decoder.container(keyedBy: CodingKeys.self)
self.title = try container.decodeIfPresent(String.self, forKey: .title)
self.id = try container.decodeIfPresent(String.self, forKey: .id)
self.purchaseDate = try! container.decodeIfPresent(Date.self, forKey: .purchaseDate)
}
public func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(id, forKey: .id)
try container.encode(title, forKey: .title)
try container.encode(purchaseDate, forKey: .purchaseDate)
}
}
// Purchase+CoreDataProperties.swift
extension Purchase {
@nonobjc public class func fetchRequest() -> NSFetchRequest<Purchase> {
return NSFetchRequest<Purchase>(entityName: "Purchase")
}
@NSManaged public var id: String?
@NSManaged public var title: String?
@NSManaged public var purchaseDate: Date?
}
//CALL
let decoder = JSONDecoder()
decoder.dataDecodingStrategy = .base64
let purchases = try decoder.decode([Purchase].self, from: value)
If i remove "purchaseDate" everything works correctly
推荐答案
有一个普遍的误解,错误大约是 Date
而不是数据
There is a general misunderstanding, the error is about Date
not Data
发生错误是因为JSON解码器默认不解码ISO8601日期。默认值为 TimeInterval
aka Double
。
The error occurs because the JSON decoder does not decode ISO8601 dates by default. The default is a TimeInterval
aka Double
.
错误消息就是这样:它期望 Double
,但发现了 String
That's what the error message says: It expects a Double
but found a String
您必须设置解码器的 DateDecodingStrategy
到 .iso8601
You have to set the DateDecodingStrategy
of the decoder to .iso8601
decoder.dateDecodingStrategy = .iso8601
并在 try中删除感叹号!
移交错误
这篇关于可编码的NSManagedObject失败,原因为ifcodeIfPresent数据类型的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!