Thread 10: Fatal error: Unexpectedly found nil while unwrapping an Optional value

Question

I am trying to make a service call to get user details however i get this error :

Thread 10: Fatal error: Unexpectedly found nil while unwrapping an Optional value

From this code :

    let urlString = "http://myURL.com/getInfo/getAccountTransactions/{accountPublicKey}"
    print(urlString)
    let requestUrl = URL(string:urlString)
    let requestURL = URLRequest(url:requestUrl!)

When i wrap the code in a guard let the code doesn't get executed because it finds nil, i am not sure why because the URL string can never be nill since its initialized with a default value on the same code.

This the code in a guard let :

    let urlString = "http://myURL.com/getInfo/getAccountTransactions/{accountPublicKey}"
    guard let requestUrl = URL(string:urlString) else { return }
    let requestURL = URLRequest(url:requestUrl)

This the entire service call code :

class TransactionServiceCall : NSObject, URLSessionDelegate{

let viewResponse = ThrowResponse()

func fetchTransactions(requestObject: Transaction, completion: @escaping (Dictionary<String,Any>?) -> Void) {
    let urlString = "http://myURL.com/getInfo/getAccountTransactions/{accountPublicKey}"

    guard let requestUrl = URL(string:urlString) else { return }
    let requestURL = URLRequest(url:requestUrl)

    let searchParams = Transaction.init(publicKey: requestObject.publicKey)
    var request = requestURL
    request.httpMethod = "POST"
    request.httpBody = try?  searchParams.jsonData()
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    let session = URLSession.shared

    let task = session.dataTask(with: request, completionHandler: { data, response, error -> Void in
        do {
            let httpResponse = response as! HTTPURLResponse
            let statusCode = httpResponse.statusCode

            if 200 ... 299 ~= statusCode {
                if let json = try JSONSerialization.jsonObject(with: data!) as? Dictionary<String,Any> {
                    self.viewResponse.dismissLoader()
                    print(json)
                    completion(json)
                }
            }else{
                self.viewResponse.dismissLoader()
                self.viewResponse.showFailureAlert(title: "Failure", message: "")
                completion(nil)
            }
        } catch {
            DispatchQueue.main.async {
                self.viewResponse.dismissLoader()
                self.viewResponse.showFailureAlert(title: "Failure", message: "")
                completion(nil)
            }
        }
    })

    task.resume()

  }

}

It is important to note that the url has curly brackets in it e.g

http://myURL.com/getInfo/getAccountTransactions/{accountPublicKey}

Answer 1

You need to escape special characters in the url string using addingPercentEncoding(withAllowedCharacters:) and an appropriate CharacterSet so that a valid URL object may be created from it.
In your case, the CharacterSet should be .urlQueryAllowed

Like so:

//The unescaped string
let unescaped = "http://myURL.com/getInfo/getAccountTransactions/{accountPublicKey}"

//The escaped string
let escaped = unescaped.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)

//...