GraphQL 1.9.3（iOS Swift）自定义标量JSON解码问题求助

你遇到的ApolloAPI.JSONDecodingError.couldNotConvert(value: AnyHashable to: Swift.String)错误，核心原因是接口返回的值被包装成了AnyHashable类型，但你的JSON扩展没有处理这种情况，直接走到了default分支抛出错误。下面是调整后的代码方案：

extension JSON: JSONDecodable, JSONEncodable {
    public init(jsonValue value: JSONValue) throws {
        switch value {
        case let string as String:
            self = string
        case let int as Int:
            self = String(int)
        case let dictionary as [String: Any]:
            guard let data = try? JSONSerialization.data(withJSONObject: dictionary, options: []) else {
                throw JSONDecodingError.couldNotConvert(value: dictionary, to: String.self)
            }
            guard let serializedJson = String(data: data, encoding: .utf8) else {
                throw JSONDecodingError.couldNotConvert(value: dictionary, to: String.self)
            }
            self = serializedJson
        case let array as [Any]:
            guard let data = try? JSONSerialization.data(withJSONObject: array, options: []) else {
                throw JSONDecodingError.couldNotConvert(value: array, to: String.self)
            }
            guard let serializedJson = String(data: data, encoding: .utf8) else {
                throw JSONDecodingError.couldNotConvert(value: array, to: String.self)
            }
            self = serializedJson
        // 新增处理AnyHashable包装值的分支
        case let hashable as AnyHashable:
            try self.init(jsonValue: hashable.base)
        default:
            throw JSONDecodingError.couldNotConvert(value: value, to: String.self)
        }
    }
    
    public var jsonValue: JSONValue {
        // 编码时将字符串转回原始JSON对象，适配接口期望的类型
        guard let data = self.data(using: .utf8),
              let jsonObject = try? JSONSerialization.jsonObject(with: data) else {
            return self
        }
        return jsonObject
    }
}

关键调整说明： #

1. 新增AnyHashable处理分支：递归解析AnyHashable包装的原始值，覆盖Apollo内部可能的包装逻辑
2. 补充数组类型处理：避免接口返回数组时同样触发解码错误
3. 替换fallthrough为明确错误抛出：原代码的fallthrough会直接走default分支，改为针对当前类型抛出错误，便于调试定位
4. 优化jsonValue实现：确保编码时能将字符串转回对应的JSON对象（如果接口期望接收原始字典/数组类型，这个调整是必要的）

内容的提问来源于stack exchange，提问作者Paresh Patel