) I'm trying to get the Error messages from the response's body to post request.
Here is the example of my code:
let task = URLSession.shared.dataTask(with: request) { _, response, error in
if let error = error {
print("Error took place \(error)")
} else {
print(response.?????)
}
What should I do to see the responses body?
You are ignoring the first parameter in the closure (_, response, error), and actually there is your data. Check the Apple sample to understand more https://developer.apple.com/documentation/foundation/url_loading_system/fetching_website_data_into_memory
Related
I am trying to perform an HTTP POST request in swift that will send some data to my server using PHP file, but it crashes with the error
Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value
The token and selectedAreaNames (the error is in the first line) are just regular strings. What could be the problem?
let url = URL(string: "https://xxxxxxx.xxx/register.php/\(token)|\ (selectedAreaNames)")! //error is here...
var request = URLRequest(url: url)
request.httpMethod = "POST"
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
if let error = error {
print("error: \(error)")
} else {
if let response = response as? HTTPURLResponse {
print("statusCode: \(response.statusCode)")
}
if let data = data, let dataString = String(data: data, encoding: .utf8) {
print("data: \(dataString)")
}
}
}
task.resume()
Assuming that’s really how your URL must look, you can do:
let url = URL(string: "https://xxxxxxx.xxx/register.php")!
.appendingPathComponent(token + "|" + selectedAreasNames)
That will percent escape those portions of the URL (including the |).
That having been said, this is an exceedingly unusual format for a POST request, which usually has the data being posted inside the body of the request, not just added as another path component of the URL. And if this was a GET request, where the parameters are added to the URL, you’d generally see this after a ? in the URL, separating the path of the request from the query. And this structure of simply TOKEN|VALUES is an unusual query structure, too.
I am trying to access the custom server response body for 500 errors in class HTTPURLResponse (URLResponse) using URLSession.shared.dataTask function. I can only have access to statusCode and allHeaderFields but it doesn't seem to help.
The equivalent in java for ex. is HttpURLConnection.getErrorStream(), but I cannot find something similar in pure swift (I would like to solve this without using 3rd party libs).
How can I get the text response for the 500 error?
let task = session.dataTask(with: urlRequest) { data, response, error in
if let data = data, let response = response as? HTTPURLResponse {
switch response.statusCode {
case 500...599:
let yourErrorResponseString = String(data: data, encoding: .utf8)
default:
break
}
}
}
There is no way you can get the response data out of HTTPURLResponse. It only contains header information.
If you want to retrieve the response data, you need to use something like dataTask(with:completionHandler:) to send your request. That function passes (Data?, URLResponse?, Error?) to your completion handler. The data parameter of the completion handler is the data returned by the server.
For example:
import Foundation
let url = URL(string: "http://httpstat.us/500")!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let data = data, let response = response as? HTTPURLResponse else {
return
}
switch response.statusCode {
case 500...599:
print(String(data: data, encoding: .utf8) ?? "No UTF-8 response data")
default:
print("not a 500")
}
}
task.resume()
Edit: Removed force unwrap according to #Rob‘s suggestion
There is no way to get more details about a 500 error from the client side.
500 is "Internal Server Error" and it's intentionally vague and unhelpful since disclosing information about the cause of the error would assist hackers in compromising the site.
However you can get a great deal of information about the error from the server log and the log for whatever was processing your code on the server side (php, etc.).
If you have access to the server logs and don't see enough information, you can increase the level of logging for the server and application.
I'm following this tutorial for making a simple REST API call in swift: https://grokswift.com/simple-rest-with-swift/
The problem I'm running into is that the data task completion handler next gets executed. When I'm debugging it step by step, it just jumps over the completion handler block. Nothing is printed in the console, either.
I've searched for other methods of making REST API calls, but they are all very similar to this one and not working, either.
Here is my code:
let endpoint: String = "https://jsonplaceholder.typicode.com/todos/1"
guard let url = URL(string: endpoint) else {
return
}
let urlRequest = URLRequest(url: url)
let session = URLSession.shared
let task = session.dataTask(with: urlRequest) { (data, response, error) -> Void in
guard error == nil else {
print("Error calling GET")
return
}
guard let responseData = data else {
print("Error receiving data")
return
}
do {
print ("Parsing response...")
}
}
task.resume()
Your code looks right to me. I tested it in a Playground and I'm getting the Parsing response... message printed to the console which makes me think the issue is elsewhere in your code or environment. I'd be happy to take a look at the whole project if you can post a Github link or something similar.
Here are the steps I would take to debug an issue like this:
1) Confirm my execution environment has an active internet connection. The Safari app can be used to confirm on iOS devices or the Simulator. Playgrounds can be tested by pasting the following lines.
let url = URL(string: "https://jsonplaceholder.typicode.com/todos/1")!
print (try? String(contentsOf: url))
Look for a line in the console output similar to:
Optional("{\n \"userId\": 1,\n \"id\": 1,\n \"title\": \"delectus aut autem\",\n \"completed\": false\n}")
2) Confirm the url is valid and returns data by pasting it into a web browser url bar and hitting enter. You will either see JSON printed in the browser or not.
3) Confirm my code is actually getting called when the application runs. You can do this with either breakpoints or print() statements. As OOPer2 pointed out asynchronous callback closures like that used in session.dataTask() execute in a different time than the rest of your code which is why "it just jumps over the completion handler block" while stepping through with the debugger. You'll need to put another breakpoint or print() statement inside the completion handler closure. I'd put the breakpoint on the guard error == nil else { line.
4) Make sure the application is still executing when the network request finishes and the completion handler closure executes. If your code is in a ViewController running in an iOS application it's probably fine, but if it's running in a Playground it may not be. Playgrounds by default stop execution once the last line of code has been evaluated which means the completion closure will never execute. You can tell a Playground to continue executing indefinitely by importing the PlaygroundSupport framework and setting needsIndefiniteExecution = true on the current Playground page. Paste the entire code block below into a Playground to see it in action:
import Foundation
import PlaygroundSupport
// Keep executing the program after the last line has evaluated so the
// closure can execute when the asynchronous network request finishes.
PlaygroundPage.current.needsIndefiniteExecution = true
// Generic Result enum useful for returning values OR an error from
// asynchronous functions.
enum Result<T> {
case failure(Error)
case success(T)
}
// Custom Errors to be returned when something goes wrong.
enum NetworkError: Error {
case couldNotCreateURL(for: String)
case didNotReceiveData
}
// Perform network request asynchronous returning the result via a
// completion closure called on the main thread.
//
// In really life the result type will not be a String, it will
// probably be an array of custom structs or similar.
func performNetworkRequest(completion: #escaping (Result<String>)->Void ) {
let endpoint: String = "https://jsonplaceholder.typicode.com/todos/1"
guard let url = URL(string: endpoint) else {
let error = NetworkError.couldNotCreateURL(for: endpoint)
completion(Result.failure(error))
return
}
let urlRequest = URLRequest(url: url)
let session = URLSession.shared
let task = session.dataTask(with: urlRequest) { (data, response, error) -> Void in
// This closure is still executing on a background thread so
// don't touch anything related to the UI.
//
// Remember to dispatch back to the main thread when calling
// the completion closure.
guard error == nil else {
// Call the completion handler on the main thread.
DispatchQueue.main.async {
completion(Result.failure(error!))
}
return
}
guard let responseData = data else {
// Call the completion handler on the main thread.
DispatchQueue.main.async {
completion(Result.failure(NetworkError.didNotReceiveData))
}
return
}
// Parse response here...
// Call the completion handler on the main thread.
DispatchQueue.main.async {
completion(Result.success("Sucessfully parsed results"))
}
}
task.resume()
}
performNetworkRequest(completion: { result in
// The generic Result type makes handling the success and error
// cases really nice by just using a switch statement.
switch result {
case .failure(let error):
print(error)
case .success(let parsedResponse):
print(parsedResponse)
}
})
Why you dont use this Library Alamofire is an HTTP networking library written in Swift.
Add this line to your Podfile
pod 'Alamofire', '~> 4.4'
Then, run the following command:
pod install
Then in your ViewController file:
import Alamofire
Alamofire.request("https://jsonplaceholder.typicode.com/todos/1").responseJSON { response in
print("Request: \(String(describing: response.request))") // original url request
print("Response: \(String(describing: response.response))") // http url response
print("Result: \(response.result)") // response serialization result
if let json = response.result.value {
print("JSON: \(json)") // serialized json response
}
If let data = response.data, let utf8Text = String(data: data, encoding: .utf8) {
print("Data: \(utf8Text)") // original server data as UTF8 string
}
}
And in here are an example of how to parse the result.
https://github.com/CristianCardosoA/JSONParser
For more info about Alamofire:
https://github.com/Alamofire/Alamofire
I hope this help.
I get the following error since I upgraded to Xcode 8:
Extra Argument In A Call
My code looks like this:
Alamofire.request(.GET, link).validate().responseJSON { response in
The error highlights link in red. It is defined further above the code:
let link = "http://www.gov.je/_layouts/15/C5.Gov.Je.CarParks/proxy.aspx"
Why do I get this error?
According to the document:
- Data Request - Simple with URL string
// Alamofire 3
Alamofire.request(.GET, urlString).response { request, response, data, error in
print(request)
print(response)
print(data)
print(error)
}
// Alamofire 4
Alamofire.request(urlString).response { response in // method defaults to `.get`
debugPrint(response)
}
So you need to remove .GET argument
let link = "http://www.gov.je/_layouts/15/C5.Gov.Je.CarParks/proxy.aspx"
Alamofire.request(link).responseJSON { response in
print(response.request) // original URL request
print(response.response) // HTTP URL response
print(response.data) // server data
print(response.result) // result of response serialization
if let JSON = response.result.value {
print("JSON: \(JSON)")
}
}
The server that I am using returns error messages in the HTTP status message. For example, it will return "400 User already exists" rather than "400 Bad Request".
I would like to access the string "User already exists" in the response method called by Alamofire. However, I cannot find any way to access this string.
I found this question on StackOverflow already: Swift Alamofire: How to get the HTTP response status code
Unfortunately, no one gives an answer to the question. :(
Here is where Chrome shows where the error is:
I would suggest trying to print out all the possible data fields that you are given and see what you can find. Please try the following example and see if that sheds any light.
let URL = NSURL(string: "your/url/to/somewhere")!
let parameters = ["foo": "bar"]
Alamofire.request(.POST, URL, parameters: parameters)
.response { request, response, data, error in
println("Request: \(request)")
println("Response: \(response)")
println("Error: \(error)")
if let data = data as? NSData {
println("Data: \(NSString(data: data, encoding: NSUTF8StringEncoding)!)")
}
}
Return response in json format from the server and then i think you'll be able to get the appropriate status.
I've implemented that thing using php codeigniter..from where my response is like
$response['status'] = 'user_already_exists';
$this->response($response, 400);
Now in swift you can go with this
Alamofire.request(.POST,URL, parameters:parameters) .responseJSON
{
(request, response, data, error) in
var json = JSON(data!) //I've used swiftyJSON for reading json response
let status = json["status"].stringValue
println("Status : \(status)")
}
Hope this may help you.