json - ARKit 4.0 – 是否可以将 ARWorldMap 数据转换为 JSON 文件？

Question

我想知道是否可以转换 worldMap二进制数据(存储空间映射状态和一组 ARAnchor)到 json或 xml文件？

func writeWorldMap(_ worldMap: ARWorldMap, to url: URL) throws {

    let data = try NSKeyedArchiver.archivedData(withRootObject: worldMap, 
                                         requiringSecureCoding: true)
    try data.write(to: url)
}

如果可能，我可以使用哪些工具？

Answer 1

恐怕唯一的方法就是将 ARWorldMap 包裹起来。对象变成 Codable像这样的对象:

struct ARData {
    var worldMap: ARWorldMap?
}

extension ARData: Codable {
    enum CodingKeys: String, CodingKey {
        case worldMap
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)

        let worldMapData = try container.decode(Data.self, forKey: .worldMap)
        worldMap = try NSKeyedUnarchiver.unarchivedObject(ofClass: ARWorldMap.self, from: worldMapData)
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        
        if let worldMap = worldMap {
            let colorData = try NSKeyedArchiver.archivedData(withRootObject: worldMap, requiringSecureCoding: true)
            try container.encode(colorData, forKey: .worldMap)
        }
    }
}

要将该对象的实例编码为 JSON，请使用 encode(:) JSONEncoder的功能:

let arData = ARData(worldMap: worldMap)
let encoder = JSONEncoder()

do {
    let jsonData = try encoder.encode(arData)
} catch {
    print(error)
}

默认情况下， JSONEncoder将转换 ARWorldMap数据转换为可以使用 JSONDecoder 读取的 Base64 字符串:

let decoder = JSONDecoder()

do {
    let decoded = try decoder.decode(ARData.self, from: jsonData)
} catch {
    print(error)
}