Variable Not Passing In POST parameter in Swift - swift

Question

I'm trying to get the cities by country using the POSTMAN Api. When I don't bring any variables into the parameter, the request works as expected. Though, when I try to use a global variable as a parameter, it returns empty. It works perfectly fine if it was coded as such: "country": "Nigeria" (everything else the same)
Code below:
let myCountry = selectedCountryString.lowercased().trimmingCharacters(in: .whitespacesAndNewlines)
guard let url = URL(string: "https://countriesnow.space/api/v0.1/countries/population/cities/filter") else {
return
}
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
let body: [String: Any] = [
"limit": 10,
"order": "dsc",
"orderBy": "value",
"country": "\(myCountry)"
]
request.httpBody = try? JSONSerialization.data(withJSONObject: body, options: .fragmentsAllowed)
let task = URLSession.shared.dataTask(with: request) {data, _, error in
guard let data = data, error == nil else {
return
}
do{
let response = try JSONDecoder().decode(CitiesPopModel.self, from: data)
onCompletion(response)
}
catch {
print("Error country -> \(myCountry)")
}
}
task.resume()
}
I switched my code to this and it is now working with the variable:
func callCitiesByPopAPI(completion: #escaping (CitiesPopModel?, Error?) -> ()) {
let url = "https://countriesnow.space/api/v0.1/countries/population/cities/filter"
let parameters: [String: Any] = [
"limit": 20,
"order": "dsc",
"orderBy": "value",
"country": selectedCountryString
]
AF.request(url, method: .post, parameters: parameters, encoding: JSONEncoding.default).responseDecodable(of: CitiesPopModel.self) { response in
if let error = response.error {
completion(nil, error)
return
}
if let result = response.value {
completion(result, nil)
print("City pop model result is \(result)")
return
}
}
}

Answer 1

Not worry about it you have to pass selectedCountryString value as like it then all goes perfectly
let selectedCountryString = "INDIA"

Answer 2

Replace value forHttpHeaderField for this:
request.setValue("application/json", forHTTPHeaderField: "Accept")
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
And replace httpBody for this:
request.httpBody = body.percentEncoded()
I tested this with Algeria, it's worked.
extension Dictionary {
func percentEncoded() -> Data? {
map { key, value in
let escapedKey = "\(key)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
let escapedValue = "\(value)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
return escapedKey + "=" + escapedValue
}
.joined(separator: "&")
.data(using: .utf8)
}
}
extension CharacterSet {
static let urlQueryValueAllowed: CharacterSet = {
let generalDelimitersToEncode = ":#[]#" // does not include "?" or "/" due to RFC 3986 - Section 3.4
let subDelimitersToEncode = "!$&'()*+,;="
var allowed: CharacterSet = .urlQueryAllowed
allowed.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
return allowed
}()
}

Answer 3

Here is my test code that shows how to fetch the data from the server,
using a variable as a parameter (country) to the POST request, and display it in a view. Works very well for me.
struct ContentView: View {
#State var cityPop = CitiesPopModel()
var body: some View {
List(cityPop.data) { data in
VStack {
Text(data.city).foregroundColor(.blue)
ScrollView(.horizontal) {
HStack {
ForEach(data.populationCounts) { pop in
VStack {
Text(pop.year)
Text(pop.sex)
Text(pop.value).foregroundColor(.blue)
}
}
}
}
}
}
.onAppear {
getCountry(country: "Australia") { result in
if let popData = result {
cityPop = popData
}
}
}
}
func getCountry(country: String, completion: #escaping(CitiesPopModel?) -> Void) {
guard let url = URL(string: "https://countriesnow.space/api/v0.1/countries/population/cities/filter") else {
return
}
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
let body: [String: Any] = [
"limit": 10,
"order": "dsc",
"orderBy": "value",
"country": country
]
request.httpBody = try? JSONSerialization.data(withJSONObject: body, options: .fragmentsAllowed)
URLSession.shared.dataTask(with: request) { data, _, error in
guard let data = data, error == nil else { return }
do {
let response = try JSONDecoder().decode(CitiesPopModel.self, from: data)
return completion(response)
}
catch {
print("Error country -> \(country)")
}
completion(nil)
}.resume()
}
}
// MARK: - CitiesPopModel
struct CitiesPopModel: Codable {
var error: Bool = false
var msg: String = ""
var data: [City] = []
}
// MARK: - City
struct City: Identifiable, Codable {
let id = UUID()
let city: String
let country: String
let populationCounts: [Population]
enum CodingKeys: String, CodingKey {
case city, country, populationCounts
}
}
// MARK: - Population
struct Population: Identifiable, Codable {
let id = UUID()
let year, value, sex, reliabilty: String
enum CodingKeys: String, CodingKey {
case year, value, sex, reliabilty
}
}