Thread 1 : signal SIGABRT error on API usage-CodePudding

I'm new to swift and currently I'm trying to learn how to use API. But I'm getting this error at my viewcontroller and appdelegate.

Here is my code:

import UIKit

class ViewController: UIViewController {
    
    @IBOutlet weak var myLabel: UILabel!
    var fetchedCountry = [Country]()

    override func viewDidLoad() {
        super.viewDidLoad()
        parseData()
    }


    func parseData(){
        let url = "https://restcountries.com/v3.1/all"
        var request = URLRequest(url: URL(string: url)!)
        request.httpMethod = "GET"
        
        let configuration = URLSessionConfiguration.default
        let session = URLSession(configuration: configuration, delegate: nil, delegateQueue: OperationQueue.main)
        
        let task = session.dataTask(with: request) { data, response, error in
            if error != nil{
                print("error!")
            }
            else{
                do{
                    
                    let fetchData = try JSONSerialization.jsonObject(with: data!, options: .mutableLeaves) as! NSArray
                    
                    
                    DispatchQueue.main.async {
                    for eachFetchedCountry in fetchData{
                        let eachCountry = eachFetchedCountry as! [String: Any]
                        let country = eachCountry["name"] as! String //Thread 1 : signal SIGABRT
                        let capital = eachCountry["capital"] as! String
                        
                        self.fetchedCountry.append(Country(country: country, capital: capital))
                    }
                    print(self.fetchedCountry)
                    print("aa")
                }
                }
                catch{
                    print("do try error")
                    
                }
            }
        }
        task.resume()
    }

class Country {
    var country : String
    var capital : String
    
    init(country: String, capital: String){
        self.capital = capital
        self.country = country
    }
}

I'm also getting this error:

Output: Could not cast value of type '__NSDictionaryI' (0x1db05bb30) to 'NSString' (0x1db05b2b0).

How can I solve this issue?

CodePudding user response：

The best solution here would be to create structs implementing the Codable protocol, that represent the answer you are getting from this API. You don´t need to decode every property but only those you are interested in.

struct CountryTransferable: Codable{
    let name: Name
    let capital: [String]?
}

struct Name: Codable {
    let common, official: String
    let nativeName: [String: Translation]?
}

struct Translation: Codable {
    let official, common: String
}

Then create another init for you Country (I´d choose a struct over a class) that can take the TransferableCountry as an argument:

struct Country {
    var country : String
    var capital : String
    
    init(country: String, capital: String){
        self.capital = capital
        self.country = country
    }
    
    init(_ transferable: CountryTransferable){
        // You can choose every other of the name or capital properties. These are just for example.
        self.country = transferable.name.official
        // As not every country seem to have a capital this can be nil
        self.capital = transferable.capital?.first ?? "unknown"
    }
}

And decoding would work this way:

if error != nil {
  print("error!")
}
else {
  do {
    // Decode to your defined transferable struct as array and map it to the Country type
    let countries = try JSONDecoder().decode([CountryTransferable].self, from: data).map{Country($0)}

    DispatchQueue.main.async {
          // assign the new values
          self.fetchedCountry = countries
      }
      print(self.fetchedCountry)
      print("aa")
    }
  } catch {
    // print something meaningfull here
    print(error)

  }
}