Swift 4 JSON decoding - json

Question

I am trying to decode JSON. My swift function for decoding the JSON is:
func GetChapInfo(){
let endpoint = "https://chapel-logs.herokuapp.com/chapel"
let endpointUrl = URL(string: endpoint)
do {
var request = URLRequest(url: endpointUrl!)
request.httpMethod = "GET"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = URLSession.shared.dataTask(with: request){
(data: Data?, response: URLResponse?, error: Error?) in
let dataAsString = String(data: data!, encoding: .utf8)
//print(dataAsString)
if(error != nil) {
print("Error")
}
else{
do{
guard let chapData = try? JSONDecoder().decode(Chapel.self, from: data!) else {
print("Error: Couldn't decode data into chapData")
return
}
for E in chapData.chap {
print(E.Day as Any)
}
}
}
}
task.resume()
}
}
my struct in Swift is
struct Chapel: Decodable {
let chap: [Chap]
}
struct Chap: Decodable {
let Name: String?
let Loc: String?
let Year: Int?
let Month: Int?
let Day: Int?
let Hour: Int?
let Min: Int?
let Sec: Int?
}
and my response from the server is:
{"chap":{"Name":"Why Chapel","Loc":"FEC","Year":2018,"Month":9,"Day":4,"Hour":16,"Min":1,"Sec":7}}
However when I run this the program prints out "Error: Couldn't decode data into chapData" and I cannot figure out why.

Answer 1

First of all catch decoding errors. Never try?. The caught error is much more descriptive
Expected to decode Array<Any> but found a dictionary instead
Means: The value for key chap is a dictionary, not an array
struct Chapel: Decodable {
let chap: Chap
}
And then you have to print
print(chapData.chap.Day)
You can reduce your code. An explicit URLRequest and headers for a default GET request is not needed. This is sufficient:
let endpoint = "https://chapel-logs.herokuapp.com/chapel"
let endpointUrl = URL(string: endpoint)!
do {
let task = URLSession.shared.dataTask(with: endpointUrl) { (data, response, error) in
...