Consume data from blockchain API - swift

Question

I'm not sure what I'm doing wrong, I've been at it for an hour, I'm trying to print 1 or 2 lines from
https://api.covalenthq.com/v1/1/address/0x8f299f2908c9Cd71e723E7059Ac52eaea3638b2E/balances_v2/?&key=ckey_4eeea29a22c14701a9844f01151
but I get an error. I tried to debug it and it seems like my model and it's call is wrong, what's going on?
import SwiftUI
struct FetchingAPI: View {
#State private var results = [Result]()
var body: some View {
Text("Fetching API")
.onAppear(perform: loadData)
}
var semaphore = DispatchSemaphore (value: 0)
func loadData() {
guard let url = URL(string: "https://api.covalenthq.com/v1/1/address/0x8f299f2908c9Cd71e723E7059Ac52eaea3638b2E/balances_v2/?&key=ckey_4eeea29a22c14701a9844f01151") else {
print("Invalid URL")
return
}
let request = URLRequest(url: url, timeoutInterval: Double.infinity)
let task = URLSession.shared.dataTask(with: request) { data, response, error in
if let data = data {
print(String(data: data, encoding: .utf8)!)
if let decodedResponse = try? JSONDecoder().decode(Response.self, from: data) {
// AFTER HERE THE DATA IS [] NON EXISTENT
DispatchQueue.main.async {
// update our UI
self.results = decodedResponse.results
}
// everything is good, so we can exit
return
}
} else {
print(String(describing: error))
semaphore.signal()
return
}
semaphore.signal()
}
task.resume()
semaphore.wait()
}
struct Response: Codable {
var results: [Result]
}
struct Result: Codable {
var data: Int
var address: String
var quote_currency: String
}
}
EDIT: Adding error message after adding suggested try catch:
I updated the code to be:
do {
if let data = data {
// print(String(data: data, encoding: .utf8)!)
let decodedResponse = try JSONDecoder().decode(Response.self, from: data)
// we have good data – go back to the main thread
DispatchQueue.main.async {
// update our UI
self.results = decodedResponse.results
}
// everything is good, so we can exit
return
}
} catch {
print("Unexpected error: \(error).")
semaphore.signal()
return
}
ERROR Message:
Unexpected error: keyNotFound(CodingKeys(stringValue: "updatedAt", intValue: nil), Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "data", intValue: nil)], debugDescription: "No value associated with key CodingKeys(stringValue: \"updatedAt\", intValue: nil) (\"updatedAt\").", underlyingError: nil)).

Answer 1

Here's how I solved it without so much code:
struct ContentView: View {
#State var address:String = ""
var body: some View {
VStack(){
Text("address: \(address)")
Button(action: {
makeApiRequest()
}, label: {
Text("make api request")
})
}
}
func makeApiRequest(){
let url = URLRequest(url: URL(string: "https://api.covalenthq.com/v1/1/address/0x8f299f2908c9Cd71e723E7059Ac52eaea3638b2E/balances_v2/?&key=ckey_4eeea29a22c14701a9844f01151")!)
URLSession.shared.dataTask(with: url) { data, responce, error in
if let data = data {
if let decodeResponce = try? JSONDecoder().decode(apiResponce.self, from: data){
address = decodeResponce.data.address
}
}
}.resume()
print(url)
}
}
struct apiResponce: Codable {
let data:apiData
let error:Bool
}
struct apiData: Codable {
let address:String
let quote_currency:String
}