Suppose, the webservice provider's server exposing the webservice in the form http://example.com:8000/api
What is best framework or library to access the webservice in ios 7 project
There are a few marshaling frameworks that support generating an object-graph from XML, however I would simply go for the following:
Invoke the service endpoint. My favorite library is BBHTTP, however you could use AFNetworking, NSURLConnection with gcd or whatever you prefer for asynch network calls.
Extract the relevant contents of the XML payload onto your use-case specific payload object using RaptureXML
I recommend having use-case specific payload objects because they model exactly what is needed for a given service invocation - supporting the notion of contract-first development. This allows you to change you internal model without effecting the integration to external systems. Similarly the external API can change without effecting your model.
You can create a category method on RXMLElement to return the element mapped to a use-case-specific object. A typical mapping usually takes just a handful of lines of code to marshal from wire-format to your payload object for the service invocation.
Here's an example (the code that I took it from wanted the payload wrapped in a SOAP envelope - just ignore that bit).
- (void)request:(MyUseCaseRequstPayload*)request onComplete:(void (^)(MyResponsePayload*))onSuccess
onError:(void (^)(NSError*))onError;
{
//Even more XML! You can stick your payload inside an envelope if you want
SoapEnvelope* envelope = [SoapEnvelope envelopeWithContent:[request xmlString]];
[[BBHTTPRequest postToURL:_serviceUrl data:[envelope data] contentType:#"text/xml"] execute:^(BBHTTPResponse* response)
{
RXMLElement* element = [RXMLElement elementFromXMLData:[response content]];
MyResponsePayload* response = [[element child:#"elementToBeMapped"] asMyObjectType];
if (onSuccess)
{
onSuccess(response);
}
} error:^(NSError* error)
{
LogDebug(#"Got error: %#", error);
if (onError)
{
onError(error);
}
}];
}
Related
I need to prevent URL encoding of one parameter value for one HTTP request in our app since it has already been encoded before being passed to AFNetworking.*
It seems like the obvious way to do this would be to use setQueryStringSerializationWithBlock on AFHTTPRequestSerializer. However, I can not figure out how to hand over to AFNetworking to do the default serialization for the cases where I don't need custom handling.
I.e. I need to be able to say (pseudo code):
[sessionManager.requestSerializer setQueryStringSerializationWithBlock:
^NSString *(NSURLRequest *request, NSDictionary *parameters, NSError *__autoreleasing *error)
{
if (request is DFP request and parameter is cust_params)
{
// do special handling
}
else
{
// do standard URL encoding for the parameter
// how?
}
}];
Essentially, for the else case, I would like to do what AFURLRequestSerialization.requestBySerializingRequest does, which is to call the static function:
AFQueryStringFromParametersWithEncoding(parameters, self.stringEncoding);
This is however not exposed outside of the AFURLRequestSerialization.m implementation file so I cannot call it.
What is the proper course of action here?
*The parameter in question is the cust_params parameter for a DFP ad-serving call, see: https://support.google.com/dfp_premium/answer/1080597
AFQueryStringFromParametersWithEncoding is private, but its implementation is exposed through the default AFHTTPRequestSerializer implementation of request parameter serialization using URL encoding. Just take the value from another instance of that in your block.
So I'm trying to support offline usage of an iOS application I'm making that uses a REST API. Here's what I have so far:
A server running with a REST interface to manipulate my data model.
An iOS application that uses RestKit to retrieve the data stored on my server.
RestKit stores server responses locally in Core Data.
When the server is unavailable I still want users to be able to update the data model and then when the server becomes available again I want those updates to be pushed to the server.
The issue I've run into is that when a value that has been updated locally (but not pushed to the server yet) is received from the server it is overwritten with the contents of the server's response. To prevent this I am trying to cancel the save to my local storage if the new 'updatedAt' date is before the current 'updatedAt' date.
This is my current validation function:
- (BOOL)validateUpdatedAt:(id *)ioValue error:(NSError **)outError
{
if(self.updatedAt && [self.updatedAt compare:((NSDate *)*ioValue)] == NSOrderedDescending) {
*outError = [NSError errorWithDomain:RKErrorDomain code:RKMappingErrorMappingDeclined userInfo:nil];
return NO;
}
return YES;
}
This works, but only prevents this individual value from being changed. I want the entire update of that object to be canceled if this one field is invalid. How do I do this?
The support available from RestKit is to set discardsInvalidObjectsOnInsert for the whole object to be discarded when validation fails. But, this won't work for you as it only works for NSManagedObject instances that are being inserted, because it uses validateForInsert:.
You could look at using validateForUpdate: to perform a similar check and then reverting the changes, but RestKit isn't really offering you anything in terms of the abort in your case.
I'm working on an app which primarily works with an API that will be installed in an internal system. The API is also accessible via the public internet. The client wants to allow users to enter both an internal and external (public internet) URL that the app will then connect to depending on availability of the internal and external URLs.
The app is basically done with the exception that it currently connects to the internal URL only for all it's API calls. I'm using AFNetworking with block-based completion/failure invocations for each API call.
Based on the logic that we have designed, the app will always check for the API's availability by querying for the server's current time. This is done by calling http://internal_url/api/time. If this API fails to return an appropriate respond, we'll switch to the external URL http://external_url/api/time and call the same API on that URL. If both fails, the app will inform the user accordingly and not perform any other queries to the API.
Without revealing too much, here's some code on how I the API calls are currently setup:
- (void)someAPIMethodCall:(NSDictionary *)parameters completionBlock:block failure:block {
// query /api/time and return the URL (internal/external) that is currently up
AFHTTPClient *client = [AFHTTPClient clientWithBaseURL:<url returned from above query>];
[client operationWithSuccess:block failure:block];
}
So my question would be: what is the best way to get the query /api/time method above to work? Obviously, this method needs to complete and return either the internal/external URL so that the subsequent actual API query could use. AFAIK, AFNetworking calls are block-based so it will return before the above /api/time returns. I've also thought of a separate class that uses NSURLConnection synchronously which will block the main-thread while it waits for the /api/time to return.
I'd like to tell you to simply use the same URL internally and externally (via DNS) but that's not what you want.
I think you're asking how to conditionally call the other url.
You want someAPIMethodCall to be asynchronous... so you don't want to block on the call to checking for the correct api to call.
Aside from caching the results so you don't have to do this every time, you simply want to call another block based method of your own that has a completion block which passes IN a parameter of the URL to call for your real query.
- (void)someAPIMethodCall:(NSDictionary *)parameters completionBlock:(void (^)(void))succesBlock failure((^)(void)):failureBlock {
[self callBlockWithMyApiUrl:^(NSString *apiUrl){
AFHTTPClient *client = [AFHTTPClient clientWithBaseURL:apiUrl];
[client operationWithSuccess:successBlock failure:failureBlock];
} onFailure:^{
failureBlock
}
}
- (NSString *)callBlockWithMyApiUrl:(NSString * (^)(void))success (void (^)(void))failure
{
// Your code to test for the working URI
// If you're doing it this way, I'd suggest caching the result.
// Subscribe to networking interface changes to dump the cache.
}
I am trying to build a Survey application where the surveys will be taken offline on multiple ipads and when these ipads are online they are going to upload the data(survey answers) to our servers? I am really struggling how to send the survey to multiple ipads and more importantly to capture from different ipads to one source ?
I need help to clear my architecture part and I need some examples to do the coding part. Do you know anything similar?
What are you ideas?
Many Thanks in advance,
Arda
Create a web server to accept and send survey questions and answers.
I would envision an app that goes like this:
1) Slave iPads makes a HTTP POST request to server asking for the survey
This is usually done using a networking library for iOS like MKNetworkKit or AFNetworking. The general process is to:
create a NSDictionary of key-value pairs to form the HTTP POST request
submit the data through a block construct with completion handler
So something like:
MKNetworkOperation *op = [engine operationWithURLString:#"http://www.mywebserver.com/api/fetchQuestions"
params:nil
httpMethod:#"POST"];
2) Server receives request, grabs all survey questions in database and return JSON encoded questions to slave ipads.
I'm not sure what platform your web server is on but in the past, I used Symfony 2.0 which is a PHP web framework.
It provides very helpful tools like Doctrine (an Object Relational Mapper or ORM) to let me work with my MySQL data as if they're programming objects.
So my general process for fetching data would be something like:
// pseudo php function codes
public function sendSurveyQuestionAction()
{
$repository = $this->getDoctrine()->getRepository('MyAppBundle:Survey');
$query = $repository->createQueryBuilder('query')->getQuery();
$arrObjs = $query->getResult();
$arrObjDatas = NULL;
foreach($arrObjs as $obj)
{
$arrObjDatas[] = $obj->toArray();
}
$response = new Response(json_encode(array('data' => $arrObjDatas)));
$response->headers->set('Content-Type', 'application/json');
$return $response;
}
This would return all survey in JSON format, ready to be parsed by your master iPad app.
3) Users on slave iPads fill in the questions through the app UI and submits. The app saves
the data to disk, checks for a working internet connection before sending data back to server.
Submitting the answer is very similar grabbing the questions, so your iOS code should be something like:
// ------------------------------------------------------------------------------------
// store all question-answers into a dictionary to be submitted as HTTP POST variables
// obviously, you wouldn't create it here, this is just example code, you would likely
// have stored your questions and answers when user presses 'finish' button
// ------------------------------------------------------------------------------------
NSMutableDictionary *paramDictionary = [[NSMutableDictionary alloc] init];
[paramDictionary setObject:#"5" forKey:#"q1"];
[paramDictionary setObject:#"10" forKey:#"q2"];
[paramDictionary setObject:#"15" forKey:#"q3"];
// this helps your web server know how many question-answers to expect, or you could hard code it into your business logic
[paramDictionary setObject:[NSNumber numberWithInteger:3] forKey:#"numberOfQA"];
MKNetworkOperation *op = [engine operationWithURLString:#"http://www.mywebserver.com/api/submitAnswers"
params:paramDictionary
httpMethod:#"POST"];
This will submit your answers for each of your question. You may have noticed I used q1, q2, q3.
These are for your web server code to identify each questions and extract the respective answers from them.
4) Server receives finished answers and commit them to database
So if you were using Symfony 2.0 PHP code, then something like:
// pseudo php function
public function saveAnswersAction()
{
$numOfQA = $_REQUEST['numberOfQA'];
for($i = 0; $i < $numOfQA; $i++)
{
// ----------------------------------------------------------------------
// looping through all the questions such as q1, q2, q3, q4, q5....
// by appending the counter variable to the question identifier
// ----------------------------------------------------------------------
$currentAnswer = $_REQUEST['q'.$i];
// use Doctrine to create new answer entities, and fill in their data
$answerEntity.answer = $currentAnswer;
$surveyEntity->addAnswerEntity($answerEntity);
// mark survey as complete so we can fetch all 'completed' surveys later
$surveyEntity.complete = true;
}
// tell Doctrine to commit changes to MySQL Database
// return HTTP OK status message
}
5) Now all that's left is for your master iPad app to make a HTTP POST request to get all surveys.
The process is the same with your iOS code making a HTTP POST requesting for all 'completed' survey entities from your web server.
The web server grabs them and return them as JSON encoded data.
Your app then receives the completed surveys with question answer like this:
surveys
{
{
questionNumber: 1,
questionAnswer: "5"
},
{
questionNumber: 2,
questionAnswer: "10"
},
{
questionNumber: 3,
questionAnswer: "15"
}
}
Now you use JSONKit to parse this JSON data. You should end up with a NSDictionary from JSONKit.
You can then go something like:
// pseudo code
-(void)displayCompletedSurveys
{
[MKNetworkOperationEngine doRequest:
...
^completionBlock {
// parse JSON data
NSDictionary *surveyData = [JSONKit dictionaryFromJSONData:data)
NSEnumerator *enumerator = [surveyData enumerator];
NSDictionary *currentQuestion = nil;
while([enumerator nextObject] != nil)
{
// do something with each of your question-answer e.g. show it on screen
}
}];
}
Points To Consider
Most of the code above are pseudo-codes. Your final real code would probably be much more in depth.
You'll need to build some master login into your app to prevent everyone from seeing the completed surveys.
Some Extra Information You Should Know
Here are some extra information to help you
JSONKit for fast JSON data decoding from your web server
MKNetworking or AFNetworking to submit your data to your web server
You need to know how to write web services to handle accepting the survey answers. I recommend learning a web framework like Symfony 2.0
Hope that helps.
I need to check status of web server, specifically, the information if the web server returns proper status code 200. Is there any way to get the HTTP response code from web server in iOS?
This is well documented in the official docs, with no need to implement a 3rd party library (although if you're new to iOS coding, a Networking API can simplify the underlying function calls). Your class must be an NSURLConnection delegate, and after making the NSURLConnection you implement the delegate method something like this:
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse*)response
{
if ([response statusCode] == 200) {
// Handle valid response (You can probably just let the connection continue)
}
else {
// Other status code logic here (perhaps cancel the NSURLConnection and show error)
}
}
You should find the URL Loading Guide very useful reading for this and other networking functions on iOS.