Sometimes I fetch information from a specific site.
But when the response is slow I would like to add a timeout function. I would like to know how.
Can I add a timeout function to the code below?
html = try String(contentsOf: url, encoding: String.Encoding.ascii)
You are not really supposed to use init(contentsOf:encoding:) to read from a remote URL. This initialiser is synchronous so while it is doing that your app's UI will freeze and the user won't be able to do anything, as you may have noticed.
You are supposed to use URLSession and URLRequest to fetch data from remote URLs. They are asynchronous so you get your data in a completion handler.
You can set a timeout in seconds when you create the URLRequest, and you will get an NSError in the completion handler if it timed out (among other reasons).
var request = URLRequest(url: URL(string: "https://example.com")!,timeoutInterval: 10)
request.addValue("text/plain", forHTTPHeaderField: "Content-Type")
request.httpMethod = "GET"
let task = URLSession.shared.dataTask(with: request) { data, response, error in
guard let data = data else {
print(String(describing: error))
return
}
let result = String(data: data, encoding: .ascii)
// do something with result
}
task.resume()
Related
I have a Firebase Cloud Function that I call from a URL rather than a function. The URL is used to load a WKWebView and the function is being called using one of the parameters in the URL, specifically the return_url.
An example of the URL to load the WKWebView would be https://domain.name?app_name=app_name&return_url=cloud_function_url.
private func loadWKWebView() {
let url = "https://domain.name"
let params = "param1=param1&return_url=\(cloud_function_url)"
var request = URLRequest(url: URL(string: url)!)
request.httpMethod = "POST"
request.httpBody = params.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request) { (data : Data?, response : URLResponse?, error : Error?) in
if data != nil {
if let returnString = String(data: data!, encoding: .utf8) {
DispatchQueue.main.async {
self.webView.loadHTMLString(returnString, baseURL: URL(string: url)!)
}
}
}
}
task.resume()
}
The URL loads an authentication page in which the user must enter their username and password and returns the parameter I need.
I can console log the parameter but I don’t know how to pass the data to my iOS application because it is not a function “directly” that is making the call to the function expecting the result. The result depends on whether the user enters a valid username and password.
How can I send the response once the user logs in to my app?
What you are putting in params is query parameters. That should be appended to the URL, not sent as data in a POST.
I suggest using a URLComponents struct to compose your URL from the parts you need (probably host plus queryItems.)
I have created a sample app in Django which deletes a question from App. And provides a correct output when consumed using POSTMAN.
class Questions(APIView):
def delete(self,request):
received_id = request.POST["id"]
print(received_id)
place = Question.objects.get(pk=received_id)
place.delete()
questions = Question.objects.all()
seriliazer = QuestionSerializer(questions,many = True)
return Response({'Orgs': seriliazer.data})
However, when I am trying to achieve it from iOS app, it's returning {"detail":"Unsupported media type "text/plain" in request."}
func deleteQuestion( id: Int){
guard let url = URL(string: "http://127.0.0.1:8000/V1/API/questions/") else {
return
}
var request = URLRequest(url: url)
let postString = "id=15"
request.httpBody = postString.data(using: String.Encoding.utf8);
request.httpMethod = "DELETE"
URLSession.shared.dataTask(with: request) { data, response, error in
let str = String(decoding: data!, as: UTF8.self)
print(str)
if error == nil {
self.fetcOrganizatinData()
}
}.resume()
}
Could not really understand where exactly the problem is ?
If the api is expecting Json, the body you are sending is not Json, it’s encoded plain text. If it should be Json you can change the body string into the Json format like:
“{\”id\”:15}”
// you may want to tell it what you’re sending
request.setValue("application/json", forHTTPHeaderField: "Accept-Encoding")
Another thing it could be is the request is missing the Accept-Encoding header which tells the api what you’re sending up where Content-Type is what the api typically sends down.
I’ve experienced header injection when I’ve sent requests through specific gateways that aren’t always right. I’d the header isn’t present, something along the way could try to help you out and add the header. This has caused me problems on the past. I still don’t know exactly where in our stack it was occurring, but adding the header fixed my problem.
You can add the header like:
request.setValue("charset=utf-8", forHTTPHeaderField: "Accept-Encoding")
DELETE request's body will be ignored, I could guess from the Is an entity body allowed for an HTTP DELETE request? post. HENCE Better to send the complete URL or in header itself,
so I made the function as below
def delete(self,request):
received_id = request.headers['id']
place = Question.objects.get(pk=received_id)
place.delete()
return HttpResponse("DELETE view is working fine ")
and swift
func deleteQuestion( id: Int){
guard let url = URL(string: "http://127.0.0.1:8000/V1/API/questions/") else {
return
}
var request = URLRequest(url: url)
//let postString = "id=\(id)"
// request.httpBody = postString.data(using: String.Encoding.utf8);
request.httpMethod = "DELETE"
request.setValue("charset=utf-8", forHTTPHeaderField: "Accept-Encoding")
request.setValue("charset=utf-8", forHTTPHeaderField: "Content-Type")
request.setValue("\(id)", forHTTPHeaderField: "id")
URLSession.shared.dataTask(with: request) { data, response, error in
let str = String(decoding: data!, as: UTF8.self)
print(str)
if error == nil {
self.fetcOrganizatinData()
}
}.resume()
}
Shortly add Content-Type application/json in your headers
Reason
this happens because the postman has some default headers usually 8.
One of them is
Content-Type text/plain
and by writing "Content-Type": "application/json" we can overwrite that rule.
So whenever you want to pass your data like JSON do that.
to learn more what is by default in postman
I recommend you to read this official documentation of postman.
It happens with me I solved this with overwriting default Content-Type
This question already has answers here:
Using NSURLSession from a Swift command line program
(3 answers)
Closed 2 years ago.
I am trying to send HTTP request with POST method in a command line app. Using JSON as body of the request. I am using session.uploadTask to send this request and use JSON data serialised from simple Dictionary. Maybe I missed something but it doesn't work. I even tried to write my request to console and it looks good -> it is the same format as iTranslate API wants.
//creating new session
let session = URLSession.shared
let url = URL(string: "https://api.itranslate.com/translate/v1")!
//setting httpMethod to POST
var request = URLRequest(url: url)
request.httpMethod = "POST"
//setting header
request.setValue("application/json", forHTTPHeaderField: "content-type")
//dictionary with json
let json = ["key": "...", "source": ["dialect":"en", "text": "How are you?"], "target": ["dialect": "es"]] as [String : Any]
//serialization from json to jsonData
let jsonData = try! JSONSerialization.data(withJSONObject: json, options: [])
let task = session.uploadTask(with: request, from: jsonData) { data, response, error in
if let data = data, let dataString = String(data: data, encoding: .utf8) {
print(dataString)
}
}
task.resume()
In most apps, there is a “run loop” that is constantly running, responding to user interaction, keeping the app alive until the user explicitly terminates it. In that scenario, we can initiate the asynchronous network request, confident that the run loop is keeping our app alive, and when the network response comes in, our completion handler closure is called.
In a command line app, on the other hand, when it gets to the end of the code, the app simply terminates, never giving the asynchronous network request a chance to respond, and the closure will never be called.
You can, however, have the command line app wait for the request to finish before terminating, e.g.
let semaphore = DispatchSemaphore(value: 0)
let task = session.uploadTask(with: request, from: jsonData) { data, response, error in
if let data = data, let dataString = String(data: data, encoding: .utf8) {
print(dataString)
}
semaphore.signal()
}
task.resume()
semaphore.wait()
Now, this technique (waiting on the main thread, thereby blocking that thread) is a very bad practice in standard apps, because it will block the main thread while the network request is running. In a typical app, blocking the main thread would freeze the UI, offering a substandard user experience (and the OS might even kill the app for not being responsive). We generally would never block the main thread.
But in a command line app, where you often don't worry about a graceful and responsive UI, blocking the main thread is less of an issue and the above can keep the app alive while the network request is running.
My question is simple: how do you call a HTTP GET Request in Swift?
I am trying to retrieve specific data from server (I have the URL string), the problem is that the previous answers I saw, doesn't explain thoroughly how to request an HTTP Get and save the retrieved information in a variable to be used later? Thanks in advance!
Here's what I have so far:
let myURL = NSURL(string:"https://api.thingspeak.com/channels/CHANNEL_ID/last_entry
_id.txt");
let request = NSMutableURLRequest(url:myURL! as URL);
request.httpMethod = "GET"
Not sure what do following requesting the GET.
In your post you are missing the part that does the actual getting to of the data.
Your code should look something like this to get the value out of the text file.
var lastID: String?
let myURL = NSURL(string:"https://api.thingspeak.com/channels/1417/last_entry_id.txt");
let request = NSMutableURLRequest(url:myURL! as URL);
//request.httpMethod = "GET" // This line is not need
// Excute HTTP Request
let task = URLSession.shared.dataTask(with: request as URLRequest) {
data, response, error in
// Check for error
if error != nil
{
print("error=\(error)")
return
}
// Print out response string
let responseString = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("responseString = \(responseString!)")
lastID = "\(responseString!)" // Sets some variable or text field. Not that its unwrapped because its an optional.
}
task.resume()
I'm trying to do a PUT request using Swift. In a REST client, when I try to do a REST request the following way:
In Body- x-www-form-urlencoded, I add vote=1 and with id being taken in the param for example: /user/:id, it works!
I try to do the same in Swift code, it does not work and I get responseString = Optional(502 Bad Gateway: Registered endpoint failed to handle the request.
Here is my code:
var baseURL = "http://<domain>/user"
let putURL = baseURL + "/\(id)"
print(putURL)
let request = NSMutableURLRequest(URL: NSURL(string: putURL)!)
request.HTTPMethod = "PUT"
let putString = "vote=1"
request.HTTPBody = putString.dataUsingEncoding(NSUTF8StringEncoding)
request.timeoutInterval = 1500
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
data, response, error in
guard error == nil && data != nil else {
print("error=\(error)")
return
}
let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
print("responseString = \(responseString)")
}
task.resume()
You forgot to set the content type, e.g.
request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
Without that, the server won't know what to do with the blob of random data that you just sent it.
I'm not saying that this is necessarily the only problem, but it is definitely a problem, and one big enough to cause the error you're seeing.