Question

当我试图解码这个json时，我得到了这个错误：

[{
    "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",
}]

致命错误：＆＃39;尝试！＆＃39;表达式意外地引发了一个错误：Swift.DecodingError.typeMismatch（Swift.Double， Swift.DecodingError.Context（codingPath：[Foundation。（_ JSONKey in _12768CA107A31EF2DCE034FD75B541C9）（stringValue：＆＃34;索引0＆＃34;，intValue：可选（0）），MyApp.Purchase.CodingKeys.purchaseDate]， debugDescription：＆＃34;预计解码Double但找到一个字符串/数据相反。＆＃34;，underlyingError：nil））：file /BuildRoot/Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-900.0.69.2/src/swift/stdlib/public/core/ErrorType.swift，第181行

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

Answer 1

存在一般性误解，错误大约是Data而不是TimeInterval

发生错误是因为默认情况下JSON解码器不会解码ISO8601日期。默认值为Double又名Double。

错误消息的内容是：它需要String，但找到了DateDecodingStrategy

您必须将解码器的.iso8601设置为decoder.dateDecodingStrategy = .iso8601

try!

删除function save($image){ header("Content-type: image/png"); $name = "png"; $save = "./image/png/". strtolower($name) ."_.png"; imagepng($image, $save); // cmBn: c = not critical; m = private; B must be capital; n = depends on image data $chunk = "cmBn"; $build_id = 2139; // Building ID (Uint32), positive values 32-bit up to 4,294,967,295 (232 − 1) $floor_id = 12345; // Floor ID (Uint8), positive values 8-bit up to 255 $max_lat = 51.897867564536452; // Max Latitude (Float) $min_long = 13.1234567890123; // Min Longitude (Float) $min_lat = 51.97867564518453; // Min Latitude (Float) $max_long = 13.2223334445551; // Max Longitude (Float) // insert a BKGD chunk into the PNG file for graceful image degradation in IE6 $pngData = bin2hex(file_get_contents($save)); $idatMarker = '200049444154'; //? $bkgdMarker = '624b4744'; //cmBn $bkgdChunk = '0006' . $bkgdMarker; //? //oreach ($bgColor as $bit) //{ //$bkgdChunkData .= '00' . dechex($bit); $bkgdChunkData .= '00' . dechex($build_id); $bkgdChunkData .= '00' . dechex($floor_id); $bkgdChunkData .= '00' . dechex($max_lat); $bkgdChunkData .= '00' . dechex($min_long); $bkgdChunkData .= '00' . dechex($min_lat); $bkgdChunkData .= '00' . dechex($max_long); //} $bkgdChunk .= $bkgdChunkData; $bkgdChunk .= dechex(crc32(pack('H*', $bkgdMarker . $bkgdChunkData))) . '0000'; $parsed = explode($idatMarker, $pngData, 2); // split file by first 'IDAT' chunk $pngData = pack('H*', $parsed[0] . $bkgdChunk . $idatMarker . $parsed[1]); file_put_contents($save, $pngData); }中的感叹号以移交错误

可编码NSManagedObject在decodeIfPresent数据类型上失败

1 个答案: