如何在Swift 4可編碼協議中使用JSON字典類型編碼屬性

Question

好吧，我的問題很簡單。 我想做與此答案相同的操作，但要進行編碼： 如何在Swift 4可解碼協議中使用JSON字典類型解碼屬性

該解決方案可以很好地與解碼配合使用，但是我還需要對Dictionary<String, Any>進行編碼

我不知道如何為KeyedEncodingContainer和其他擴展編寫擴展，以及編寫什么方法。

Answer 1

您可以通過根據問題的答案改編可解碼代碼段來實現

extension KeyedEncodingContainerProtocol where Key == JSONCodingKeys {
    mutating func encodeJSONDictionary(_ value: Dictionary<String, Any>) throws {
        try value.forEach({ (key, value) in
            let key = JSONCodingKeys(key: key)
            switch value {
            case let value as Bool:
                try encode(value, forKey: key)
            case let value as Int:
                try encode(value, forKey: key)
            case let value as String:
                try encode(value, forKey: key)
            case let value as Double:
                try encode(value, forKey: key)
            case let value as Dictionary<String, Any>:
                try encode(value, forKey: key)
            case let value as Array<Any>:
                try encode(value, forKey: key)
            case Optional<Any>.none:
                try encodeNil(forKey: key)
            default:
                throw EncodingError.invalidValue(value, EncodingError.Context(codingPath: codingPath + [key], debugDescription: "Invalid JSON value"))
            }
        })
    }
}

extension KeyedEncodingContainerProtocol {
    mutating func encode(_ value: Dictionary<String, Any>, forKey key: Key) throws {
        var container = self.nestedContainer(keyedBy: JSONCodingKeys.self, forKey: key)
        try container.encodeJSONDictionary(value)
    }

    mutating func encodeIfPresent(_ value: Dictionary<String, Any>?, forKey key: Key) throws {
        if let value = value {
            try encode(value, forKey: key)
        }
    }

    mutating func encode(_ value: Array<Any>, forKey key: Key) throws {
        var container = self.nestedUnkeyedContainer(forKey: key)
        try container.encodeJSONArray(value)
    }

    mutating func encodeIfPresent(_ value: Array<Any>?, forKey key: Key) throws {
        if let value = value {
            try encode(value, forKey: key)
        }
    }
}

extension UnkeyedEncodingContainer {
    mutating func encodeJSONArray(_ value: Array<Any>) throws {
        try value.enumerated().forEach({ (index, value) in
            switch value {
            case let value as Bool:
                try encode(value)
            case let value as Int:
                try encode(value)
            case let value as String:
                try encode(value)
            case let value as Double:
                try encode(value)
            case let value as Dictionary<String, Any>:
                try encode(value)
            case let value as Array<Any>:
                try encode(value)
            case Optional<Any>.none:
                try encodeNil()
            default:
                let keys = JSONCodingKeys(intValue: index).map({ [ $0 ] }) ?? []
                throw EncodingError.invalidValue(value, EncodingError.Context(codingPath: codingPath + keys, debugDescription: "Invalid JSON value"))
            }
        })
    }

    mutating func encodeJSONDictionary(_ value: Dictionary<String, Any>) throws {
        var nestedContainer = self.nestedContainer(keyedBy: JSONCodingKeys.self)
        try nestedContainer.encodeJSONDictionary(value)
    }
}

這是一個代碼片段

但是，此代碼段將在Swift 4.1中失敗，該版本應在2018年上半年發布。