iOS - UI Label Not Updating - swift

Question

I am trying to build a weather app with AlamoFire and i am getting the JSON Response as expected but when i am trying to update the date to UI Label, my variable is returning a nil. if anyone get a chance to let me know where i am going wrong
import UIKit
class WeatherVC: UIViewController {
#IBOutlet weak var dateLbl: UILabel!
#IBOutlet weak var weatherType: UILabel!
#IBOutlet weak var cityname: UILabel!
#IBOutlet weak var currentTemp: UILabel!
var weatherConstants = WeatherConstant()
override func viewDidLoad() {
super.viewDidLoad()
// updateUI()
//
weatherConstants.downloadCurrentWeather {
self.updateUI()
}
weatherConstants = WeatherConstant()
print(Current_Weather_Url)
}
func updateUI() {
weatherType.text = weatherConstants.weatherType
cityname.text = weatherConstants.cityName
print("current city name is \(weatherConstants.weatherType)")
}
}
Weather Constants
import UIKit
import Alamofire
class WeatherConstant {
var _cityName :String!
var _currentTemp : Double!
var _weatherType : String!
var _highTemp : String!
var _date :String!
var cityName :String {
if _cityName == nil {
_cityName = ""
}
return _cityName
}
var currentTemp : Double{
if _currentTemp == nil {
_currentTemp = 0.0
}
return _currentTemp
}
var weatherType : String {
if _weatherType == nil {
_weatherType = ""
}
return _weatherType
}
var highTemp : String {
if _highTemp == nil {
_highTemp = ""
}
return _highTemp
}
var date : String {
if _date == nil {
_date = ""
}
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .none
let currentDate = dateFormatter.string(from: Date())
self._date = "Today, \(currentDate)"
return _date
}
//func downloadWeatherDetails(completed : DownloadComplete) ===> downloadWeatherDetails(completed : #escaping DownloadComplete)
func downloadCurrentWeather(completed: #escaping DownloadComplete) {
Alamofire.request(Current_Weather_Url).responseJSON{ response in
let result = response.result
// print(result)
debugPrint(result)
if let dict = result.value as? Dictionary<String, AnyObject>{
if let name = dict["name"] as? String {
self._cityName = name
print("current name is \(self._cityName)")
}
if let currentTemp = dict["weather"] as? [Dictionary<String, AnyObject>] {
if let main = currentTemp[0]["main"] as? String{
self._weatherType = main
print("Current Weather Type \(self._weatherType)")
}
}
}
completed()
}
}
}
JSON Response
https://samples.openweathermap.org/data/2.5/weather?lat=35&lon=139&appid=e9a34088739f38c517b4a45084f5ed82
SUCCESS: {
base = stations;
clouds = {
all = 0;
};
cod = 200;
coord = {
lat = "35.02";
lon = "139.01";
};
dt = 1485792967;
id = 1907296;
main = {
"grnd_level" = "1013.75";
humidity = 100;
pressure = "1013.75";
"sea_level" = "1023.22";
temp = "285.514";
"temp_max" = "285.514";
"temp_min" = "285.514";
};
name = Tawarano;
sys = {
country = JP;
message = "0.0025";
sunrise = 1485726240;
sunset = 1485763863;
};
weather = (
{
description = "clear sky";
icon = 01n;
id = 800;
main = Clear;
}
);
wind = {
deg = 311;
speed = "5.52";
};
}
Current Weather Type Optional("Clear")----> this the weather type i am trying to provide to UIlabel
current city name is Optional("") ------> Here i am trying to print what data is in UILabel but its returning empty string
2018-08-07 11:18:09.567868-0700 WeatherApp1.1[82321:3248301] [BoringSSL] Function boringssl_session_errorlog: line 2881 [boringssl_session_read] SSL_ERROR_ZERO_RETURN(6): operation failed because the connection was cleanly shut down with a close_notify alert

Answer 1

You're overwriting the weatherConstants value with a new object in viewDidLoad. Try removing that.
(Longer explanation: you're correctly creating a weatherConstants object, and asking it to fetch data. But while that's happening, you create a second instance of that object which overwrites the first. So while the first instance completes the network request and tells your UI to redraw, the UI is getting its data from the second instance of WeatherConstants)