Swift 5 Json Parse from post Request - ios

Question

I am trying to parse JSON data from a post request and I am struggling with the outcome. I would like to parse the JSON data in the Swift 5 programming language.
I have spent hours trying to figure this out. I am very confused on how to deal with multiple levels of hiarchy like this.
I dont need all the data i just need time and total_amount_sent.
Swift
struct Response: Codable {
var txs: [ResponseData]
enum CodingKeys: String, CodingKey {
case txs
}
}
struct ResponseData: Codable {
var time: String?
var total_amount_sent: String?
var recipient: String?
var txid: String?
var amount: String?
}
let url = URL(string: paramURL)!
let json: [String: Any] = [
"key": "value"
]
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.httpBody = try? JSONSerialization.data(withJSONObject: json)
let task = URLSession.shared.dataTask(with: request, completionHandler: { [weak self] (data, response, error) in
do {
let json = try JSONDecoder().decode(Response.self, from: data!)
print(json)
json.txs.forEach { charge in
let transaction_time = charge.time
let transaction_txid = charge.txid
let transaction_total_amount_sent = charge.total_amount_sent
print(transaction_time)
print(transaction_txid)
print(transaction_total_amount_sent)
}
} catch {
print("Error! \(error)")
}
})
task.resume()
Error:
Error! keyNotFound(CodingKeys(stringValue: "txs", intValue: nil),
Swift.DecodingError.Context(codingPath: [], debugDescription: "No
value associated with key CodingKeys(stringValue: "txs", intValue:
nil) ("txs").", underlyingError: nil))
JSON:
{
"status" : "success",
"data" : {
"network" : "DOGETEST",
"txs" : [
{
"txid" : "df4ac3ecfc356d9e10325cd4043a4103602599b71a91ea96cb3fa3204c61264c",
"from_green_address" : false,
"time" : 1620076250,
"confirmations" : 5,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "2.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "d983739751a6170d336016ffa1b7d7f2849a4a81cb0021e03a2cc6d76c55379d",
"from_green_address" : false,
"time" : 1620076071,
"confirmations" : 6,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "2.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "1dce7dd99f6a655ca82a94c8e088576c78e4ece94995f2f90891b8f5f31a54db",
"from_green_address" : false,
"time" : 1620076021,
"confirmations" : 6,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "8.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "27719e8fae3bb64f1ecec8ac64a2135d1ccc5d9219040dceaec9d24e4b17a466",
"from_green_address" : false,
"time" : 1620075780,
"confirmations" : 6,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "4.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "2a6547411b15442b78b118981cf5632e3faedec8941aea22453d8837807d37be",
"from_green_address" : false,
"time" : 1620075743,
"confirmations" : 7,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "2.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "63a145cbdc48c1e644fa52a30ed26d66c58b685698104a549001d0fe539816ba",
"from_green_address" : false,
"time" : 1620075697,
"confirmations" : 7,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "4.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "ff350583e0cb1396a3d5cc09350697daf111626ec5a3b893f8e936276f1c6715",
"from_green_address" : false,
"time" : 1620075677,
"confirmations" : 7,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "2.00000000"
}
],
"senders" : [
"2MtSgfBmXzZv6raD7yyuGzFamzBzQD7G6Rf"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
},
{
"txid" : "5a0115a9f608f3d01caee03587253fc58e0ad0c602f4e95e6c0db1e11703af84",
"from_green_address" : false,
"time" : 1619998414,
"confirmations" : 227,
"amounts_received" : [
{
"recipient" : "2N3ZbAaJqtxD5jfbLDZichV6SSHZ6PBYPmi",
"amount" : "1000.00000000"
}
],
"senders" : [
"2MytwDpHWpdoVYQ7JzYwBPxQ5XsEdiV7udZ"
],
"confidence" : 1.0,
"propagated_by_nodes" : null
}
]
}
}

Answer 1

Your model was not properly structured.
struct Response: Decodable {
var txs: [ResponseData]
enum CodingKeys: CodingKey {
case data
}
enum ValueCodingKeys: CodingKey {
case txs
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let nestedContainer = try container.nestedContainer(keyedBy: ValueCodingKeys.self, forKey: .data)
txs = try nestedContainer.decode([ResponseData].self, forKey: .txs)
}
}
struct ResponseData: Decodable {
var time: Int?
var txid: String?
var amountsReceived: [AmoutReceived]
}
struct AmoutReceived: Decodable {
var recipient: String?
var amount: String?
}
Use .convertFromSnakeCase.
Hope you are handling error cases properly. Here is the code
func fetch(urlString: String, callback: #escaping (Result<Response, Error>) -> Void) {
guard let url = URL(string: urlString) else { return }
URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data else {
if let error = error {
callback(.failure(error))
}
return
}
do {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let result = try decoder.decode(Response.self, from: data)
callback(.success(result))
} catch {
callback(.failure(error))
}
}.resume()
}

Answer 2

You can use tools such as Quicktype.io to create a model from a JSON. This is an example model from your provided JSON. You can play around with this tool, and also there is an option "Renders output in a Swift 5 compatible mode" since you are asking about parsing in Swift 5 programming language.
import Foundation
struct User: Codable {
let status: String
let data: DataClass
}
struct DataClass: Codable {
let network: String
let txs: [Tx]
}
struct Tx: Codable {
let txid: String
let fromGreenAddress: Bool
let time, confirmations: Int
let amountsReceived: [AmountsReceived]
let senders: [String]
let confidence: Int
let propagatedByNodes: JSONNull?
enum CodingKeys: String, CodingKey {
case txid
case fromGreenAddress = "from_green_address"
case time, confirmations
case amountsReceived = "amounts_received"
case senders, confidence
case propagatedByNodes = "propagated_by_nodes"
}
}
struct AmountsReceived: Codable {
let recipient, amount: String
}
class JSONNull: Codable, Hashable {
public static func == (lhs: JSONNull, rhs: JSONNull) -> Bool {
return true
}
public var hashValue: Int {
return 0
}
public init() {}
public required init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
if !container.decodeNil() {
throw DecodingError.typeMismatch(JSONNull.self, DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "Wrong type for JSONNull"))
}
}
public func encode(to encoder: Encoder) throws {
var container = encoder.singleValueContainer()
try container.encodeNil()
}
}