how to not get empty array in swift playground? - ios

Question

I'm getting response from API's but I am not able to get emails array back, what am I doing wrong?
I tried to add DispatchQueue.main.asyn { emails.append(result.data.email) } but its the same result.
// MARK: - Response Class
struct Response: Codable {
let data: DataClass
let support: Support
}
// MARK: - DataClass
struct DataClass: Codable {
let id: Int
let email, firstName, lastName: String
let avatar: String
enum CodingKeys: String, CodingKey {
case id, email
case firstName = "first_name"
case lastName = "last_name"
case avatar
}
}
// MARK: - Support
struct Support: Codable {
let url: String
let text: String
}
let urls = [
URL(string: "https://reqres.in/api/users/1"),
URL(string: "https://reqres.in/api/users/3"),
URL(string: "https://reqres.in/api/users/10")
]
func getEmailFromAPI(urls: [URL?]) -> [String] {
var emails: [String] = []
for url in urls {
URLSession.shared.dataTask(with: URLRequest(url: url!)) { data, response, error in
guard let data = data else { return }
guard let result = try? JSONDecoder().decode(Response.self, from: data) else { return }
print(result.data.email)
emails.append(result.data.email)
}.resume()
}
return emails
}
print(getEmailFromAPI(urls: urls))
Please advice as to what am I doing wrong, Thanks.

Answer 1

"return emails" statement will get executed before your array gets loaded with data because of the async operation.
So you can use closure to pass the emails as per below
func getEmailFromAPI(urls: [URL?], emailResult: #escaping ([String]?) -> Void) {
var emails: [String] = []
for url in urls {
URLSession.shared.dataTask(with: URLRequest(url: url!)) { data, response, error in
if error != nil {
emailResult(nil)
}else {
guard let data = data else { return }
print(result.data.email)
emails.append(result.data.email)
emailResult(emails)
}
}.resume()
}
}
Suggestion - prefer to not append email operation instead create a codable object for the same