https://medium.com/@michaellong/how-to-chain-api-calls-using-swift-5s-new-result-type-and-gcd-56025b51033c

ResultWithDSemaphore.swift

func makeAPICall() -> Result<String?, NetworkError> {
    let path = "https://jsonplaceholder.typicode.com/todos/1"
    guard let url = URL(string: path) else {
        return .failure(.url)
    }
    var result: Result<String?, NetworkError>!
    
    let semaphore = DispatchSemaphore(value: 0)
    URLSession.shared.dataTask(with: url) { (data, _, _) in
        if let data = data {
            result = .success(String(data: data, encoding: .utf8))
        } else {
            result = .failure(.server)
        }
        semaphore.signal()
    }.resume()
    _ = semaphore.wait(wallTimeout: .distantFuture)
//     if semaphore.wait(timeout: .now() + 15) == .timedOut {
//         result = .failure(.timeout)
//     }
    return result
}