net web service that returns true or false but i don't know how to catch that response in my IOS App.
My service updates data in a database and i know it works the data gets updated it's catch the response that is the problem, i like to know so i can tell the user if something went wrong.
For those of you that know c# its a bool method, just simple try catch and return true or false.
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
//What to write here to catch my true or false
if(response) {
//true
} else {
//false
}
}
Thank you for your help
You should implementconnection:didReceiveData: to get and save NSData and – connectionDidFinishLoading: where you can interpret received data as BOOL.
basically didReceiveResponse: only get to you know about server response to your request not the entire answer.
You should check the response's HTTP status code, e.g.:
NSInteger statusCode = [(NSHTTPURLResponse*)response statusCode];
The status code for a successful request uses the range [200..299].
For example a successful GET request would be indicated with a 200 (OK).
A successful POST request will be indicated with a 201 (Created).
A successful DELET request will be indicated with a 204 (No Content)..
See also: wiki List of HTTP status codes.
Furthermore, you need to check the kind of data the server sent to you:
NSString* mimeType = [response MIMEType];
The mime type has been sent by the server in the Content-Type header of the response.
See also wiki MIME Internet Media Type
What you actually get fully depends on your request AND the server.
For example, the server may always answer with a JSON as content type. In this case, the header Content-Type of the response would be application/json. The actual JSON which represents the answer, will be related to the status code as well.
In order to provide a nice human readable message to the user, you need to consult the web service API and figure out how it is specified. Certain web service APIs may have a considerable large API. Unfortunately, some web services lack a comprehensive documentation.
Related
I'm working with a really strange (and nasty) API that I have no control over, and unfortunately when an invalid request is made, instead of responding with a 4xx status, it responds with a 200 status instead.
With this response, it also changes the response body from the usual XML response to plain text, but does not change the content type header. You can imagine how annoying this is!
I've got Siesta working with the API and the fact that it is no actually RESTful in the slightest, but I'm unsure how to get the next part working - handling the unsuccessful requests.
How do I go about transforming a technically valid and successful 200 response, into an error response? Right now I have the following setup:
configure("/endpoint") {
$0.mutateRequests { req in
... perform some mutation to request ...
}
$0.pipeline[.parsing].add(self.XMLTransformer)
}
configureTransformer("/endpoint") {
($0.content as APIResponse)
.data()
.map(Resource.init)
}
This is working just fine when the response actually is XML, however in the scenario where the response is an error, I receive the following:
bad api request: invalid api key
or something similar to this. The XMLParser class is already handling this, and in turn marks itself as having come across an error, however I don't know how to make Siesta realise that there is an error, and to not call my transformer but instead mark the request as failed to I can handle the error elsewhere.
How can I achieve what I'm after?
configureTransformer is just a common-case shortcut for the full-featured (but more verbose) arbitrary transformers Siesta’s pipeline supports. Full transformers can arbitrarily convert any response to any other, including success → failure and failure → success. The user guide discusses this a bit.
You can see this in action in the example project, which has a customer transformer that does something very similar to what you want, turning a 404 failure into a success with the content false. It is configured here and defined here. That example does a failure → success transformation, but you should find the code adaptable for your success → failure purposes.
Our application makes use of RESTful service calls using NSURLSession. The calls themselves are routed through a reverse proxy, to aide in session management, security, etc. on the backend. The only problem we're having is related to authentication. When a user attempts to access a protected resource -- either through a browser or a REST call -- and they are not authenticated, the reverse proxy displays an HTML login page.
The problem is, we'd like to leverage NSURLSession's ability to handle authentication challenges automatically. However, NSURLSession is unable to recognize that we're getting back an authentication challenge, because no HTTP 401 or other error code is being returned to the client. The reverse proxy sends back a 200, because the HTML was delivered successfully. We're able to recognize that it is the login page by inspecting the HTML within the client, but we'd like to be able to handle the authentication using a custom NSURLAuthenticationChallenge, if at all possible, so that NSURLSession can retry requests after authentication is successful.
Is there any way for us to recognize that we're getting back a login page within our completionHandler and tell NSURLSession that we're really getting back an authentication challenge? Or does NSURLSession require that we receive back an HTTP error code (401, etc.)
A couple of possibilities come to mind.
If you're using the delegate rendition of NSURLSession, you might be able to detect the redirect to the authentication failure page via NSURLSessionTaskDelegate method willPerformHTTPRedirection.
You can probably also detect the redirect by examining the task's currentRequest.URL and see if a redirect happened there, too. As the documentation says, currentRequest "is typically the same as the initial request (originalRequest) except when the server has responded to the initial request with a redirect to a different URL."
Assuming that the RESTful service generally would not be returning HTML, you can look at the NSURLResponse, confirm that it's really a NSHTTPURLResponse subclass, and then look at allHeaderFields to confirm whether text/html appears in the Content-Type of the response. This obviously only works if the authentication page returns a Content-Type that includes text/html and the rest of your responses don't (e.g. they're application/json or something like that).
Anyway, that might look like:
NSString *contentType = [self headerValueForKey:#"Content-Type" response:response];
if ([contentType rangeOfString:#"text/html"].location != NSNotFound) {
// handle it here
}
Where, headerValueForKey might be defined as follows:
- (NSString *)headerValueForKey:(NSString *)searchKey response:(NSURLResponse *)response
{
if (![response isKindOfClass:[NSHTTPURLResponse class]])
return nil;
NSDictionary *headers = [(NSHTTPURLResponse *) response allHeaderFields];
for (NSString *key in headers) {
if ([searchKey caseInsensitiveCompare:key] == NSOrderedSame) {
return headers[key];
}
};
return nil;
}
At worst, you could detect the HTML response and parse it using something like HPPLE and programmatically detect the authentication HTML response.
See Wenderlich's article How to Parse HTML on iOS.
Frankly, though, I would prefer to see a REST response to report the authentication error with a REST response (or a proper authentication failure challenge or a non 200 response) rather than a redirect to a HTML page. If you have an opportunity to change the server response, that would be my personal preference.
Authentication challenges are triggered by the WWW-Authenticate header in a 40x response.
From the documentation :
The URL loading system classes do not call their delegates to handle request challenges unless the server response contains a WWW-Authenticate header. Other authentication types, such as proxy authentication and TLS trust validation do not require this header.
Unfortunately the proxy authentication referred to above does not apply in your reverse proxy/accelerator scenario.
Have you tried simply setting the username and password to the authorization header of NSMutableURLRequest as such.
NSString *authorizationString = [[[NSString stringWithFormat:#"%#:%#",user, password] dataUsingEncoding:NSUTF8StringEncoding] base64Encoding];
[yourRequest setValue:[NSString stringWithFormat:#"Basic %#", authorizationString] forHTTPHeaderField:#"Authorization"];
This should work.
You could try using an HTML Parser library (like https://github.com/nolanw/HTMLReader).
Then in the completion handler block, you can evaluate the response to check if it is an HTML page, and if it contains a login form.
I don't know this library, but I guess you can use it like this:
HTMLDocument *document = [HTMLDocument documentWithString:responseObjectFromServer];
HTMLNode *node = [document firstNodeMatchingSelector:#"form.login"];
if(node) {
// Perform second NSURLSession call with login data
}
I'm working with an API that sends back HTTP 406's for many different errors, along with a custom message (reason phrase). It may look something like:
406 Not Acceptable: User is already logged in
406 Not Acceptable: Missing password field
406 Not Acceptable: Node does not exist.
I can get the 406 status code and the standard "Not Acceptable" string using:
NSHTTPURLResponse *HTTPResponse = (NSHTTPURLResponse *)response;
NSInteger statusCode = [HTTPResponse statusCode];
[NSHTTPURLResponse localizedStringForStatusCode:HTTPResponse.statusCode];
However I really require the reason phrase message to know how to handle the response. How can I get it, preferably using the standard iOS SDK?
I really require the reason phrase message to know how to handle the response.
Then the API is broken. The reason phrase is a debugging aid only. It's not meant to inform client behaviour.
From RFC 2616 § 6.1.1:
The Status-Code is intended for use by automata and the Reason-Phrase is intended for the human user. The client is not required to examine or display the Reason- Phrase.
If there is information about the response that cannot be conveyed by the status code alone, the proper place for it is as a header or in the response body. The reason phrase is not a correct place to put information necessary for a client to use.
Status code 406 means that the server cannot respond with the accept-header specified in the request.
406 Not Acceptable The requested resource is only capable of generating content not acceptable according to the Accept headers sent in the request.
These error codes are not iOS-specific. If you want to display different messages based on different occurrence reasons, I suppose you should check it with your API/web server, and use conditions in your code to display your custom messages for each of them.
Ultimately, you can get the reason phrase using the ASIHTTPRequest library.
http://allseeing-i.com/ASIHTTPRequest/
It was just as simple to use in my case as AFNetworking and NSURLSession.
In Delphi, I'm using Indy's TIdHTTPWebBrokerBridge coupled with TIdHTTP to send/receive data via HTTP. On the Server, I don't have any fancy handling, I always just respond with a simple content stream. If there's any issues, I only return information about that issue in the response content (such as authentication failed, invalid request, etc.). So, on the client side, can I assume that every successful request I make to this server will always have a response code of 200 (OK)?
I'm wondering because on the client, the requests are wrapped inside functions which return just a boolean for the success of the request.
Inside this function:
IdHTTP.Get(SomeURL, AStream);
Result:= IdHTTP.ResponseCode = 200;
This function handles any and every request which could possibly fetch data. If there were any issues in the request, This function should return False. In my scenario, since I always return some sort of content on the server, would the client always receive a response code of 200 in this function?
I guess the real question is, if I always return some sort of content and handle all exceptions on the server, then will the server always return status code of 200 to each request?
"Does every successful HTTP request always return status code 200?"
See w3.org: HTTP/1.1 Status Code Definitions (RFC 2616)
The answer is No. All 2xx are considered successful.
That may depend on the HTTP method used.
Should your web-server application always return 200 upon success? That may as well depend on the request method and the signal it intends for the client . e.g.
for PUT method (emphasis is mine):
If an existing resource is modified, either the 200 (OK) or 204 (No
Content) response codes SHOULD be sent to indicate successful
completion of the request.
for POST method:
The action performed by the POST method might not result in a resource
that can be identified by a URI. In this case, either 200 (OK) or 204
(No Content) is the appropriate response status, depending on whether
or not the response includes an entity that describes the result.
If a resource has been created on the origin server, the response
SHOULD be 201 (Created) and contain an entity which describes the
status of the request and refers to the new resource, and a Location
header (see section 14.30). Responses to this method are not
cacheable, unless the response includes appropriate Cache-Control or
Expires header fields. However, the 303 (See Other) response can be
used to direct the user agent to retrieve a cacheable resource.
As you can learn from the RCF, every method SHOULD have it's own success status codes, depending on the implementation.
Your other question:
"can I assume that every successful request I make to this server will always have a response code of 200 (OK)?"
You can always expect Status code 200, if your web server always responds with Status 200. Your web server application controls what response it returns to the client.
That said, Status code 200 is the Standard response for successful HTTP requests (The actual response will depend on the request method used), and in the real world of web servers, SHOULD be set as default upon successful request, unless told otherwise (As explained in Remy's answer).
To answer your specific question:
can I assume that every successful request I make to this server will always have a response code of 200 (OK)?
The answer is Yes, because TIdHTTPWebBrokerBridge wraps TIdHTTPServer, which always sets the default response code to 200 for every request, unless you overwrite it with a different value yourself, or have your server do something that implicitly replies with a different response code (like Redirect() which uses 302, or SmartServeFile() which uses 304), or encounter an error that causes TIdHTTPServer to assign a 4xx or 5xx error response code.
However, in general, what others have told you is true. On the client side, you should handle any possible HTTP success response code, not just 200 by itself. Don't make any assumptions about the server implementation.
In fact, TIdHTTP already handles that for you. If TIdHTTP encounters a response code that it considers to be an error code, it will raise an EIdHTTPProtocolException exception into your code. So if you don't get an exception, assume the response is successful. You don't need to check the response code manually.
If there is a particular response code that normally raises an exception but you do not want it to, you can specify that value in the optional AIgnoreReplies parameter of TIdHTTP.Get() or TIdHTTP.DoRequest(). Or, if you are are using an up-to-date Indy 10 SVN revision, a new hoNoProtocolErrorException flag was recently added to the TIdHTTP.HTTPOptions property so the EIdHTTPProtocolException exception is not raised for any response code.
Successful resposes are 2xx List_of_HTTP_status_codes
i did the following. Process straight all 200`s and LOG exceptions. worked, not a single non 200 - except unauthorized and timeouts (password or sometimes unavaliable server). but many/all responses will be considered for a wide range of mainstream apps.
while (iRedo < 3) do begin
s := Self.HTTPComponent.Get( sUrl );
if self.HTTPComponent.ResponseCode = 200 then begin
break;
end;
// IDEIA - log what happend if not 200
logWhatHappend( s, HTTPComponent ); // then log content, headers, etc
inc( iRedo ); sleep( 5 );
end;
I am making a POST request with RestSharp (on windows phone 7.1 client). I sent string to a service in a request body. Looks like the service is successfully called and it returns proper value (integer), however response object is null:
client.ExecuteAsync<T>(request, (response) => {
data = response.Data; // response is null in debugger
});
I cant understand why is that so.
<T> isn't a valid value for that call. I'm not sure that would even build there unless you've wrapped it in a generic method.
Also, is the response coming back as plain text? What's the Content-Type returned? Most likely, you should just use ExecuteAsync(request, callback) without the generic parameter and grab the data out of response.Content which is a string of the response body. response.Data is for the automatically deserialized XML or JSON (or custom) response if you use the generic method overload that specifies a type to deserialize to.
This seems to be an ongoing issue with RestSharp asynchronous calls - for HTTP transport errors ErrorException object is useless (returns null). Check the StatusCode property if it returns with anything but HttpStatusCode.OK. StatusDescription is not extremely useful either as it doesn't match complete status message from server response payload.