Swift 解码和编码自定义类型

Question

我在用 Swift 解码和编码我的一个类时遇到了困难。我曾尝试遵循Encoding and Decoding Custom Types 文档，但没有成功。

我的班级布局如下：

public struct MapLocation: Identifiable, Codable {
    @DocumentID public var id: String?
    let originLocation: [MapLandmark]
    let destinationLocation: [MapLandmark]
    enum CodingKeys: String, CodingKey {
        case originLocation
        case destinationLocation
    }
}

---

import Foundation
import MapKit    
struct MapLandmark: Codable {
    let placemark: MKPlacemark
    var id: UUID {
        return UUID()
    }
    var name: String {
        self.placemark.name ?? ""
    }
    var title: String {
        self.placemark.title ?? ""
    }
    var coordinate: CLLocationCoordinate2D {
        self.placemark.coordinate
    }
}

我已尝试从上述链接添加编码和解码类，但一直出错。实施解决方案的最佳方式是什么？

编辑： 我忘了提到我得到的错误是：

“类型'MapLandmark'不符合协议'Decodable'”

“类型'MapLandmark'不符合协议'Encodable”

Answer 1

MKPlacemark 符合 NSSecureCoding。您可以只使用NSKeyedArchiver 和NSKeyedUnarchiver 对其进行编码/解码。 UUID 已经符合 Codable。尝试如下：

import MapKit

extension NSSecureCoding {
    func archived() throws -> Data {
        try NSKeyedArchiver.archivedData(withRootObject: self, requiringSecureCoding: false)
    }
}

---

extension Data {
    func unarchived<T: NSSecureCoding>() throws -> T? {
        try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(self) as? T
    }
}

---

struct MapLandmark: Codable {
    let placemark: MKPlacemark
    let id: UUID
    func encode(to encoder: Encoder) throws {
        var unkeyedContainer = encoder.unkeyedContainer()
        try unkeyedContainer.encode(placemark.archived())
        try unkeyedContainer.encode(id)
    }
    public init(from decoder: Decoder) throws {
        var container = try decoder.unkeyedContainer()
        placemark = try container.decode(Data.self).unarchived()!
        id = try container.decode(UUID.self)
    }
}