Decode Array<Any> and Dictionary<String, Any> Swift

import Foundation

// Inspired by https://gist.github.com/mbuchetics/c9bc6c22033014aa0c550d3b4324411a

struct JSONCodingKeys: CodingKey {
    var stringValue: String

    init?(stringValue: String) {
        self.stringValue = stringValue
    }

    var intValue: Int?

    init?(intValue: Int) {
        self.init(stringValue: "\(intValue)")
        self.intValue = intValue
    }
}


extension KeyedDecodingContainer {

    func decode(_ type: Dictionary<String, Any>.Type, forKey key: K) throws -> Dictionary<String, Any> {
        let container = try self.nestedContainer(keyedBy: JSONCodingKeys.self, forKey: key)
        return try container.decode(type)
    }

    func decodeIfPresent(_ type: Dictionary<String, Any>.Type, forKey key: K) throws -> Dictionary<String, Any>? {
        guard contains(key) else {
            return nil
        }
        return try decode(type, forKey: key)
    }

    func decode(_ type: Array<Any>.Type, forKey key: K) throws -> Array<Any> {
        var container = try self.nestedUnkeyedContainer(forKey: key)
        return try container.decode(type)
    }

    func decodeIfPresent(_ type: Array<Any>.Type, forKey key: K) throws -> Array<Any>? {
        guard contains(key) else {
            return nil
        }
        return try decode(type, forKey: key)
    }

    func decode(_ type: Dictionary<String, Any>.Type) throws -> Dictionary<String, Any> {
        var dictionary = Dictionary<String, Any>()

        for key in allKeys {
            if let if let boolValue = try? decode(Bool.self, forKey: key) {
                dictionary[key.stringValue] = boolValue
            } else if let stringValue = try? decode(String.self, forKey: key) {
                dictionary[key.stringValue] = stringValue
            } else intValue = try? decode(Int.self, forKey: key) {
                dictionary[key.stringValue] = intValue
            } else if let doubleValue = try? decode(Double.self, forKey: key) {
                dictionary[key.stringValue] = doubleValue
            } else if let fileMetaData = try? decode(Asset.FileMetadata.self, forKey: key) {
                dictionary[key.stringValue] = fileMetaData // Custom contentful type.
            } else if let nestedDictionary = try? decode(Dictionary<String, Any>.self, forKey: key) {
                dictionary[key.stringValue] = nestedDictionary
            } else if let nestedArray = try? decode(Array<Any>.self, forKey: key) {
                dictionary[key.stringValue] = nestedArray
            }
        }
        return dictionary
    }
}

extension UnkeyedDecodingContainer {

    mutating func decode(_ type: Array<Any>.Type) throws -> Array<Any> {
        var array: [Any] = []
        while isAtEnd == false {
            if let value = try? decode(Bool.self) {
                array.append(value)
            } else if let value = try? decode(Double.self) {
                array.append(value)
            } else if let value = try? decode(String.self) {
                array.append(value)
            } else if let nestedDictionary = try? decode(Dictionary<String, Any>.self) {
                array.append(nestedDictionary)
            } else if let nestedArray = try? decode(Array<Any>.self) {
                array.append(nestedArray)
            }
        }
        return array
    }

    mutating func decode(_ type: Dictionary<String, Any>.Type) throws -> Dictionary<String, Any> {

        let nestedContainer = try self.nestedContainer(keyedBy: JSONCodingKeys.self)
        return try nestedContainer.decode(type)
    }
}

Thanks for this code!

One of our API's returned an array where one of the values was 'null', which got the [Any] decoder into an infinite loop.
Fixed it this way:

mutating func decode(_ type: Array<Any>.Type) throws -> Array<Any> {
        var array: [Any] = []

        while isAtEnd == false {
            // When one of the values is `null`, we seem to enter an infinite loop.. Check if the value is null and continue if so
            do {
                let value: String? = try decode(String?.self)
                if value == nil {
                    // Found a nil value... skip the rest of this function and continue with the next value
                    continue
                }
            } catch {
                // if we fail, it isn't a String? and isn't nil
                // continue with testing values
            }

            if let value = try? decode(Bool.self) {
                array.append(value)

            } else if let value = try? decode(Int.self) {
                array.append(value)

            } else if let value = try? decode(Double.self) {
                array.append(value)

            } else if let value = try? decode(String.self) {
                array.append(value)

            } else if let nestedDictionary = try? decode(JSON.self) {
                array.append(nestedDictionary)

            } else if let nestedArray = try? decode(Array<Any>.self) {
                array.append(nestedArray)
            }
        }
        return array
    }

@ChiellieNL thanks for sharing that fix! I had to replace the line with JSON.self to the original line to get it to compile on my end.

Here is my version with decoding (original post), encoding (thank you @sakrist!) and the null fix from above. I also changed the types to the modern syntax of [Any] instead of Array<Any>, and [String: Any] instead of Dictionary<String, Any>.

https://gist.github.com/mikebuss/17142624da4baf9cdcc337861e256533

@converted2mac I guess Github doesn't give notifications for comments on Gists 🤔

Anyway, no license, i'd say go ahead and use the code as you need ;-)

@mikebuss null value should be appended to the array as well. There were a couple of bugs including 2 infinite loops for encoding/decoding [Any]. I've created a new version that works well with all cases and fixed all the bugs that I found.
https://gist.github.com/sukov/d3834c0e7b72e4f7575f753b352f6ddd

Thanks for sharing this! I really need it :)

Thanks for this. I think if you renamed the gist to end in .swift instead of [space]Swift syntax highlighting will be added.

Thanks for sharing this 👍

i tried @sukov version, but i still saw the same issues:
null were not appended to [Any].
One infinite loop and one stack overflow in UnkeyedDecodingContainer::decode()
Here's my updated version

Is this supposed to be able to decode a struct with an [Any] parameter automatically? Or we need to manually decode it?

I'm pondering... would this GIST code help me to decode the JSON from Alpha Vantage's TimeSeriesDaily?
https://www.alphavantage.co/query?function=TIME_SERIES_DAILY&symbol=IBM&apikey=demo
Which has this JSON:

`{
    "Meta Data": {
        "1. Information": "Daily Prices (open, high, low, close) and Volumes",
        "2. Symbol": "IBM",
        "3. Last Refreshed": "2022-07-01",
        "4. Output Size": "Compact",
        "5. Time Zone": "US/Eastern"
    },
    "Time Series (Daily)": {
        "2022-07-01": {
            "1. open": "141.0000",
            "2. high": "141.6700",
            "3. low": "139.2600",
            "4. close": "141.1200",
            "5. volume": "4012106"
        },
        "2022-06-30": {
            "1. open": "139.5800",
            "2. high": "142.4600",
            "3. low": "139.2800",
            "4. close": "141.1900",
            "5. volume": "4878020"
        },
....
        
        "2022-02-08": {
            "1. open": "137.2300",
            "2. high": "137.5200",
            "3. low": "135.7800",
            "4. close": "137.0200",
            "5. volume": "4181825"
        }
    }
}

I'm wondering how to use the code... How do I specify the Dictionary of some number of Daily Dictionaries, for the JSON parsers?

struct Result: Codable {
    let metaData: MetaData
    let timeSeriesDaily: TimeSeriesDaily

    private enum CodingKeys: String, CodingKey {
        case metaData = "Meta Data"
        case timeSeriesDaily = "Time Series (Daily)"
    }
}

struct  DailyTimeSeries:  Codable {    //  use CoadableExtension  for Dictionary  [String: Any]
    let daily:  [String: DailyQuote]
}

I've banged my head on this a lot over the last few weeks. Finally a solution:

struct Daily: Codable {
    let open: String
    let high: String
    let low: String
    let close: String
    let volume: String
    
    private enum CodingKeys: String, CodingKey {
        case open = "1. open"
        case high = "2. high"
        case low = "3. low"
        case close = "4. close"
        case volume = "5. volume"
    }
}
struct MetaData: Codable {
    let information: String
    let symbol: String
    let lastRefreshed: String
    let outputSize: String
    let timeZone: String

    private enum CodingKeys: String, CodingKey {
        case information = "1. Information"
        case symbol = "2. Symbol"
        case lastRefreshed = "3. Last Refreshed"
        case outputSize = "4. Output Size"
        case timeZone = "5. Time Zone"
    }
}

struct Result: Codable {
    let metaData: MetaData
    let timeSeriesDaily:  [String:Daily]

    private enum CodingKeys: String, CodingKey {
        case metaData = "Meta Data"
        case timeSeriesDaily = "Time Series (Daily)"
    }
}

@loudmouth thank you so much for sharing!