Call completion Handler function using “Result”

问题

How to use call getEmployee function while using "Result"?

struct Employee {
    let name: String
    let designation: String
}

func getEmployee(name: String, completion: @escaping(Result<Employee?, Error>) -> Void) {

}

回答1:

First you need to make your structure conform to Codable

struct Employee: Codable {
    let name, designation: String
}

Than you need to fetch your data from your server and call completion if decoding was successful with your employee .success(employee) or if it fails pass failure with your error .failure(error):

---

func getEmployee(name: String, completion: @escaping(Result<Employee, Error>) -> Void) {
    URLSession.shared.dataTask(with: URL(string: "http://www.example.com/getEmployee.api?name=\(name)")!) { data, response, error in
        guard let data = data, error == nil else {
            if let error = error { completion(.failure(error)) }
            return
        }
        do {
            let employee = try JSONDecoder().decode(Employee.self, from: data)
            completion(.success(employee))
        } catch {
            completion(.failure(error))
        }
    }
}

---

Usage:

getEmployee(name: "Ella") { result in
    switch result {
    case let .success(employee):
        print("employee:", employee)
    case let .failure(error):
        print("error:", error)
    default: break
    }
}

来源：https://stackoverflow.com/questions/62205663/call-completion-handler-function-using-result