swift cannot dig into JSONDecoder data got via alamofire - json

Question

Cannot read data from section "weather" of JSONDecoder file, got via Almofire
the data printed in console:
{"coord":{"lon":-0.13,"lat":51.51},"weather":[{"id":521,"main":"Rain","description":"shower
rain","icon":"09d"}],"base":"stations","main":{"temp":289.64,"pressure":1006,"humidity":48,"temp_min":286.48,"temp_max":292.59},"visibility":10000,"wind":{"speed":1},"clouds":{"all":85},"dt":1558190870,"sys":{"type":1,"id":1414,"message":0.009,"country":"GB","sunrise":1558152298,"sunset":1558208948},"id":2643743,"name":"London","cod":200}
struct MyWeatherData: Codable {
let coord : coord
let weather : weather
}
struct coord: Codable {
let lon: Double
let lat: Double
}
struct weather: Codable {
let array : [unknown] //here is my problem
let base : String
}
struct unknown : Codable {
let id : Int
let main: String
let description : String
let icon : String
}
let cityLink = "https://api.openweathermap.org/data/2.5/weather?q=London"
Alamofire.request(self.cityLink+"&APPID=\(self.myId)").responseJSON { (response) in
// print("Request: \(String(describing: response.request))") // original url request
// print("Response: \(String(describing: response.response))")
// print("Result: \(response.result)")
if let data = response.data, let utf8 = String(data: data, encoding: .utf8) {
print("Data is: \(utf8)")
do {
let myData = try JSONDecoder().decode(MyWeatherData.self, from: data)
// print("lat is: \(myData.coord.lat)") //ok, working
print("weather is: \(myData.weather.main)") //not working
} catch let myError {
print("error is: ", myError)
}
}
}

Answer 1

No, the problem is not here is my problem, the problem is in MyWeatherData.
Please read the JSON. It's very easy. The value for key weather is wrapped in [] so the object is an array.
And name all structs with uppercase letters to avoid confusion like let weather : weather
struct MyWeatherData : Decodable {
let coord : Coord
let weather : [Weather]
}
struct Coord : Decodable {
let lon: Double
let lat: Double
}
struct Weather : Decodable {
let id : Int
let main: String
let description : String
let icon : String
}

Answer 2

Please name your class/Models with first letter Capitalized.
The problem is that weather is an Array on MyWeatherData so it becomes:
struct MyWeatherData: Codable {
let coord : Coord
let weather : [Weather]
}
struct Coord: Codable {
let lon: Double
let lat: Double
}
struct Weather: Codable {
let id : Int
let main: String
let description : String
let icon : String
}

Answer 3

In MyWeatherData the weather property should have [weather] type, as the JSON returns an array in weather key:
{
"coord": {
"lon": -0.13,
"lat": 51.51
},
"weather": [{
"id": 521,
"main": "Rain",
"description": "shower rain",
"icon": "09d"
}],
"base": "stations",
"main": {
"temp": 289.64,
"pressure": 1006,
"humidity": 48,
"temp_min": 286.48,
"temp_max": 292.59
},
"visibility": 10000,
"wind": {
"speed": 1
},
"clouds": {
"all": 85
},
"dt": 1558190870,
"sys": {
"type": 1,
"id": 1414,
"message": 0.009,
"country": "GB",
"sunrise": 1558152298,
"sunset": 1558208948
},
"id": 2643743,
"name": "London",
"cod": 200
}
So your types should look like this:
struct MyWeatherData: Codable {
let coord: coord
let weather: [weather]
let base: String
}
struct coord: Codable {
let lon: Double
let lat: Double
}
struct weather : Codable {
let id : Int
let main: String
let description : String
let icon : String
}
And then you can get weather instance by myWeatherData.weather.first