iOS: forcing server to provide updated data - ios

I'm working on an iPad app that requests data from a server, changes and submits it, and then re-requests the data from the server, displaying it to the user. The app updates the data just fine (the equivalent web app sees the update happening), but the data that the iPad app gets back is the old data. I thought maybe it was the caching flag on the NSURLRequest, but it doesn't look like it.
Here is my sequence of calls:
NSString* currentStuff = self.fCurrentIndex.currentStuff;
NSError* err = nil;
[self.fCurrentIndex approve:currentStuff withUsername:username andPassword:password error:&err];
if (err == nil)
{
// rebuild the case list (grab the data from the URL again first)
[self getCaseListViaURL]; // grab the updated data
[self setupUIPanel]; // display it
}
Here's the code that grabs the data (the 'getCaseListViaURL' call):
NSURLResponse* response;
NSError* err = nil;
NSMutableDictionary * jsonObject = nil;
NSString * urlRequestString;
urlRequestString = [method to get the URL string];
NSURL * url = [NSURL URLWithString:urlRequestString];
NSURLRequest * request = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:60];
NSData * data = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:&err];
if (err == nil)
{
jsonObject = [NSJSONSerialization JSONObjectWithData:data
options:NSJSONReadingMutableContainers
error:&err];
}
if (err && error) {
*error = err;
}
return jsonObject;
Is there any way to force the server to serve up the updated data?
Thanks in advance.
EDIT: Per comments, I'm adding the sequence of update to the server and subsequent pull:
This does the push to the server:
NSString* currentStuff = self.fCurrentIndex.currentStuff;
NSError* err = nil;
[self.fCurrentPatient approveStuff:currentStuff withUsername:username andPassword:password error:&err];
Where 'approveStuff' eventually calls:
__block NSData * jsonData;
__autoreleasing NSError * localError = nil;
if (!error) {
error = &localError;
}
// Serialize the dictionary into JSON
jsonData = [NSJSONSerialization dataWithJSONObject:data
options:NSJSONWritingPrettyPrinted
error:error];
if (*error) return nil;
NSURLResponse* response;
NSString * urlRequestString;
urlRequestString = [self urlStringForRelativeURL:relativeURL
withQueryParams:params];
NSURL * url = [NSURL URLWithString:urlRequestString];
NSMutableURLRequest * request;
request = [NSMutableURLRequest requestWithURL:url
cachePolicy:self.cachePolicy
timeoutInterval:self.timeOutInterval];
[request setHTTPMethod:#"POST"];
[request setHTTPBody:jsonData];
[request setValue:#"application/json;charset=UTF-8" forHTTPHeaderField:#"Content-Type"];
jsonData = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:&localError];
NSMutableDictionary * jsonObject;
if (localError == nil)
{
jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData
options:NSJSONReadingMutableContainers
error:&localError];
}
if (error && localError) {
*error = localError;
}
return jsonObject;
Right after this, I call the aforementioned get call and rebuild the UI. Now, if I stick a breakpoint when I do the get, and check on the web server if the data is updated after the push, I see the data is there. However, when I let the get operation continue, it gives me the old data.

So it looks like the issue was on the server. There were some data structures on the server side that weren't being refreshed when the data was being posted.

Related

Post request with raw body using NSURLSession

I have stuck here. Below is my code for Post request with raw body using NSURLSession. I got response = NULL and no error.
NSString* stringRequest = #"https://chocudan.com/api/shops/by_ids";
NSURL* urlRequest = [NSURL URLWithString:stringRequest];
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:urlRequest];
request.HTTPMethod = #"POST";
NSString* bodyRequest = #"563c268b84ba489c4729f149";
//I have to tried a base64 convert here but still not work.
//request.HTTPBody = [NSData base64DataFromString:bodyRequest];
request.HTTPBody = [bodyRequest dataUsingEncoding:NSUTF8StringEncoding];
NSURLSessionConfiguration* configureSession = [NSURLSessionConfiguration defaultSessionConfiguration];
configureSession.HTTPAdditionalHeaders = #{#"Content-Type" : #"application/json charset=utf-8",
#"Content-Lenght" : #"180"};
NSURLSession* session = [NSURLSession sessionWithConfiguration:configureSession];
NSURLSessionDataTask* dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSHTTPURLResponse* respHttp = (NSHTTPURLResponse*) response;
if (!error && respHttp.statusCode == 200) {
NSDictionary* respondData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
NSLog(#"%#", respondData);
}else{
NSLog(#"%#", error);
}
}];
[dataTask resume];
I have to try with postman and everything work fine. This is pictures.
Thank in advance.
Try changing it too
NSArray* bodyArray = #[#"563c268b84ba489c4729f149"]
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:bodyArray
options:NSJSONWritingPrettyPrinted error:&error];
request.HTTPBody = jsonData;
My raw data was like :
{
"email":"test#gmail.com",
"password":"12345678"
}
and what I did is :
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
[dict setValue:#"test#gmail.com" forKey:#"email"];
[dict setValue:#"12345678" forKey:#"password"];
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict
options:NSJSONWritingPrettyPrinted error:&error];
request.HTTPBody = jsonData;
This fixed it for me:
let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
configuration.HTTPAdditionalHeaders = ["Content-Type" : "text/plain"]
I guess that it was not data that was null but respondData was null?
That is because your service sends an Array with exactly one Object. JSONSerialisation creates an NSArray from that with one NSDictionary in it. The dictionary has the keys _id, contact and so on.
So it is
NSArray* respondData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
BTW
NSHTTPURLResponse* respHttp = (NSHTTPURLResponse*) response;
does not make much of a sense but does not harm either.
With respect to the body of your request, see mihir's answer. He is just right.
It may help you understanding mihir's point when you do this:
NSString* bodyRequest = #"[563c268b84ba489c4729f149]";
However, this is rather quick & dirty but may help you understanding the principles. Once understood you will certainly follow mihir's suggestion.
If you want to post raw, and param is a format of NSString, you only need to do this:
NSData *param_data = [encry_str dataUsingEncoding:NSUTF8StringEncoding];
murequest.HTTPBody = param_data;
If we can’t get anything from that response, notice that the response serializer is correct. Any additional settings, please deal it with server.

the arabic string is not readable when load json

Code:
+(id)loadJSONDataFromURL:(NSString *)urlString{
MsgsHelper *msg=[[MsgsHelper alloc]init];
// This function takes the URL of a web service, calls it, and either returns "nil", or a NSDictionary,
// describing the JSON data that was returned.
NSError *error;
NSURL *url = [NSURL URLWithString:urlString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:#"GET"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
// Call the web service, and (if it's successful) store the raw data that it returns
NSURLResponse *response = nil; //
NSData *data = [ NSURLConnection sendSynchronousRequest:request returningResponse: &response error:&error ];
//here we get the respond from NSURLResponse and then we check for the statusCode //1
//200 is ok,, 0 is no internet connection else is server error //2
NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;//1
//any warning like this one with integers shuold add the casting (int)
int statCode = (int)[httpResponse statusCode];//2
if(statCode == 200){
if (!data)
{
//NSLog(#"Download Error: %#", error.localizedDescription);
return nil;
}
// Parse the (binary) JSON data from the web service into an NSDictionary object
id dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
if (dictionary == nil) {
//NSLog(#"JSON Error: %#", error);
return nil;
}
return dictionary;
}else if(statCode == 0){
[msg alertStatus:NSLocalizedString(#"No internet", #"Message") :#"" :0 ];
return nil;
}else{
//Server Error
//NSLog(#"Server Error");
[msg alertStatus:NSLocalizedString(#"Server Error", #"Message") :#"" :0 ];
return nil;
}}
the problem on result as below:
results: (
{
"Name" = "\U0633\U0639\U0648\U062f \U0639\U0628\U062f\U0627\U0644\U0639\U0632\U064a\U0632 \U064a\U0646 \U062c\U062f\U064a\U062f";
"location" = CENTER;
}
)
maybe need to dataUsingEncoding to read arabic string, but how do it.
Thanks,

How to parse JSONP in Objective-C?

I am retrieving JSON information for an API and it says on the API that it is in JSON but I noticed it is in JSONP or "json with padding" as some call it. I tired to look everywhere to find how to parse this but no luck. The information I am trying to receive is this:
({"book":[{"book_name":"James","book_nr":"59","chapter_nr":"3","chapter":
{"16":{"verse_nr":"16","verse":"For where envying and strife is, there is confusion and
every evil work."}}}],"direction":"LTR","type":"verse"});
The link to the data is https://getbible.net/json?p=James3:16, so you can look at it directly.
This is the code I am using to try to retrieve the JSON Data and parse it into a NSMutableDictionary.
-(void)fetchJson {
NSString *currentURL = [NSString stringWithFormat:#"https://getbible.net/json?p=James"];
NSURL *url = [NSURL URLWithString:currentURL];
NSData *data = [[NSData alloc]initWithContentsOfURL:url];
NSURLRequest *theRequest = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60];
NSMutableData *receivedData = [[NSMutableData alloc] initWithLength:0];
NSURLConnection * connection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self startImmediately:YES];
[receivedData setLength:0];
NSURLResponse *response = [[NSURLResponse alloc] initWithURL:url MIMEType:#".json" expectedContentLength:-1 textEncodingName:nil];
expectedTotalSize = [response expectedContentLength];
if ([data length] !=0) {
NSLog(#"appendingData");
[receivedData appendData:data];
if(connection){
NSLog(#"Succeeded! Received %lu bytes of data",(unsigned long)[receivedData length]);
}
NSError *error;
NSDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];
if(jsonResponse){
NSArray *responseArr = [jsonResponse mutableCopy];
NSLog(#"%lu",(unsigned long)[responseArr count]);
}else if (!jsonResponse){
//do internet connection error response
}
}
}
The results I am getting back from putting a breakpoint in the code is:
jsonResponse returns NULL
NSError NSCocoaErrorDomain code - 3840
but my NSData *data is returning 15640 bytes.
My console is displaying this from the NSLogs I used for debugging:
2014-04-20 01:27:31.877 appendingData
2014-04-20 01:27:31.879 Succeeded! Received 15640 bytes of data
I am receiving the data correctly but I am not parsing it correctly I know the error is because the JSON is in JSONP format. If anyone could please help with this I would appreciate it so much. I have tired to give as much detail on this question as I can but if you need more information just let me know so I can add it and make this as clear as possible.
Your code has at least two separate attempts to download the data. Neither is really correct. The code also only works with JSON, not JSONP.
Try this:
NSURL *url = [NSURL URLWithString:#"https://getbible.net/json?p=James"];
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
if (data) {
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSRange range = [jsonString rangeOfString:#"("];
range.location++;
range.length = [jsonString length] - range.location - 2; // removes parens and trailing semicolon
jsonString = [jsonString substringWithRange:range];
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *jsonError = nil;
NSDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&jsonError];
if (jsonResponse) {
// process jsonResponse as needed
} else {
NSLog(#"Unable to parse JSON data: %#", jsonError);
}
} else {
NSLog(#"Error loading data: %#", error);
}
}];
One problem is that the data you're downloading has extraneous information at the beginning and end. The JSON being delivered by your URL is:
({"book":[{"book_name":"James","book_nr":"59","chapter_nr":"3","chapter":{"16":{"verse_nr":"16","verse":"For where envying and strife is, there is confusion and every evil work."}}}],"direction":"LTR","type":"verse"});
As the error message you're seeing indicates: you need to remove the initial ( from the beginning of the string and the ); from the end so that your JSON will start with the dictionary that your code expects. You can do this by calling subdataWithRange: on your NSData object:
NSData* jsonData = [data subdataWithRange:NSMakeRange(1, data.length-3)];
NSDictionary* jsonResponse = [NSJSONSerialization JSONObjectWithData:jsonData
options:0
error:&error];
Just to update everyone, the NSURLRequest has been deprecated in iOS9. I tried the answer by #rmaddy, and I didn't receive anything either (just like what #lostAtSeaJoshua was encountering I guess). I have updated rmaddy's answer to reflect the NSURLSession implementation that has (I think) replaced NSURLRequest:
NSURLSession *session = [NSURLSession sharedSession];
NSURL *url = [NSURL URLWithString:#"http://somerandomwebsite.com/get.php?anotherRandomParameter=5"];
[[session dataTaskWithURL:url
completionHandler:^(NSData *data,
NSURLResponse *response,
NSError *error) {
// handle response
if (data) {
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"stringJSONed: %#",jsonString);
//Do something with the received jsonString, just like in # rmaddy's reply
} else {
NSLog(#"Error loading data: %#", error);
}
}] resume];
Just a heads up notice, when I first ran it, it gave me the security error. What you need to do (if you are using http) is to add this to your plist:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>
I have to mention that after the NSAllowArbitraryLoads key, there are most probably other keys and values, such as NSExceptionDomain. But they're not really relevant to this answer I think. If you need to look further, let me know and I will dig deeper :)

NSURLConnection wrong order

I have a NSURLConnection (two of them), and they're running in the wrong order.
Here's my method:
- (void)loginToMistarWithPin:(NSString *)pin password:(NSString *)password {
NSURL *url = [NSURL URLWithString:#"https://mistar.oakland.k12.mi.us/novi/StudentPortal/Home/Login"];
//Create and send request
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
[request setHTTPMethod:#"POST"];
NSString *postString = [NSString stringWithFormat:#"Pin=%#&Password=%#",
[self percentEscapeString:pin],
[self percentEscapeString:password]];
NSData * postBody = [postString dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:postBody];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
{
// do whatever with the data...and errors
if ([data length] > 0 && error == nil) {
NSError *parseError;
NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:data options:0 error:&parseError];
if (responseJSON) {
// the response was JSON and we successfully decoded it
NSLog(#"Response was = %#", responseJSON);
} else {
// the response was not JSON, so let's see what it was so we can diagnose the issue
NSString *loggedInPage = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"Response was not JSON (from login), it was = %#", loggedInPage);
}
}
else {
NSLog(#"error: %#", error);
}
}];
//Now redirect to assignments page
NSURL *homeURL = [NSURL URLWithString:#"https://mistar.oakland.k12.mi.us/novi/StudentPortal/Home/PortalMainPage"];
NSMutableURLRequest *requestHome = [[NSMutableURLRequest alloc] initWithURL:homeURL];
[request setHTTPMethod:#"POST"];
[NSURLConnection sendAsynchronousRequest:requestHome queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *homeResponse, NSData *homeData, NSError *homeError)
{
// do whatever with the data...and errors
if ([homeData length] > 0 && homeError == nil) {
NSError *parseError;
NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:homeData options:0 error:&parseError];
if (responseJSON) {
// the response was JSON and we successfully decoded it
NSLog(#"Response was = %#", responseJSON);
} else {
// the response was not JSON, so let's see what it was so we can diagnose the issue
NSString *homePage = [[NSString alloc] initWithData:homeData encoding:NSUTF8StringEncoding];
NSLog(#"Response was not JSON (from home), it was = %#", homePage);
}
}
else {
NSLog(#"error: %#", homeError);
}
}];
}
- (NSString *)percentEscapeString:(NSString *)string
{
NSString *result = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
(CFStringRef)string,
(CFStringRef)#" ",
(CFStringRef)#":/?#!$&'()*+,;=",
kCFStringEncodingUTF8));
return [result stringByReplacingOccurrencesOfString:#" " withString:#"+"];
}
So, it's two NSURLConnection's that are added to the [NSOperationQueue mainQueue]. What my output is showing me is that the second NSURLConnection is running before the first one. So it tries to go to the page where I download data before I'm logged in, so it (obviously) returns a "You're not logged in" error.
How do I schedule them one after another?
The issue, as I suspect you have realized, is that you're doing asynchronous network requests (which is good; you don't want to block the main queue), so there's no assurance of the order they'll finish.
The quickest and easiest answer is to simply put the call to the second request inside the completion block of the first one, not after it. You don't want to be making that second one unless the first one succeeded anyway.
To keep your code from getting unwieldy, separate the login from the request for main page. And you can use the completion block pattern which is common with asynchronous methods. You add a parameter to loginToMistarWithPin that specifies what it should do when the request finishes. You might have one completion block handler for success, and one for failure:
- (void)loginToMistarWithPin:(NSString *)pin password:(NSString *)password success:(void (^)(void))successHandler failure:(void (^)(void))failureHandler {
NSURL *url = [NSURL URLWithString:#"https://mistar.oakland.k12.mi.us/novi/StudentPortal/Home/Login"];
//Create and send request
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
[request setHTTPMethod:#"POST"];
NSString *postString = [NSString stringWithFormat:#"Pin=%#&Password=%#",
[self percentEscapeString:pin],
[self percentEscapeString:password]];
NSData * postBody = [postString dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:postBody];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
{
// do whatever with the data...and errors
if ([data length] > 0 && error == nil) {
NSError *parseError;
NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:data options:0 error:&parseError];
if (responseJSON) {
// the response was JSON and we successfully decoded it
NSLog(#"Response was = %#", responseJSON);
// assuming you validated that everything was successful, call the success block
if (successHandler)
successHandler();
} else {
// the response was not JSON, so let's see what it was so we can diagnose the issue
NSString *loggedInPage = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"Response was not JSON (from login), it was = %#", loggedInPage);
if (failureHandler)
failureHandler();
}
}
else {
NSLog(#"error: %#", error);
if (failureHandler)
failureHandler();
}
}];
}
- (void)requestMainPage {
//Now redirect to assignments page
NSURL *homeURL = [NSURL URLWithString:#"https://mistar.oakland.k12.mi.us/novi/StudentPortal/Home/PortalMainPage"];
NSMutableURLRequest *requestHome = [[NSMutableURLRequest alloc] initWithURL:homeURL];
[requestHome setHTTPMethod:#"GET"]; // this looks like GET request, not POST
[NSURLConnection sendAsynchronousRequest:requestHome queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *homeResponse, NSData *homeData, NSError *homeError)
{
// do whatever with the data...and errors
if ([homeData length] > 0 && homeError == nil) {
NSError *parseError;
NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:homeData options:0 error:&parseError];
if (responseJSON) {
// the response was JSON and we successfully decoded it
NSLog(#"Response was = %#", responseJSON);
} else {
// the response was not JSON, so let's see what it was so we can diagnose the issue
NSString *homePage = [[NSString alloc] initWithData:homeData encoding:NSUTF8StringEncoding];
NSLog(#"Response was not JSON (from home), it was = %#", homePage);
}
}
else {
NSLog(#"error: %#", homeError);
}
}];
}
Then, when you want to login, you can do something like:
[self loginToMistarWithPin:#"1234" password:#"pass" success:^{
[self requestMainPage];
} failure:^{
NSLog(#"login failed");
}];
Now, change those successHandler and failureHandler block parameters to include whatever data you need to pass back, but hopefully it illustrates the idea. Keep your methods short and tight, and use completion block parameters to specify what an asynchronous method should do when it's done.
Can you check the below link. It is about forcing one operation to wait for another.
NSOperation - Forcing an operation to wait others dynamically
Hope this helps.

How to load images from ftp? [iOS]

There are, for example, 100 JSON files and appropriate 100 images on my ftp server.
1.With loading JSON where are no bug (I hope)
NSString *recipesPath = #"ftp://.../recipes/";
NSString *recipeFileName = [NSString stringWithFormat:#"00001.json", recipeCode];
NSString *recipeFileFullPath = [recipesPath stringByAppendingString:recipeFileName];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:recipeFileFullPath]];
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSError *error = nil;
NSDictionary *recipeDictionary = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
2.But images can not be loaded
NSString *recipeImageName = #"recipeImages/00001-1.jpg";
NSString *recipeImageFullPath = [recipesPath stringByAppendingString:recipeImageName];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:recipeImageFullPath]];
if (request) {
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
if (responseData) {
UIImage *image = [UIImage imageWithData:responseData];
}
}
responseData nearly always is nil.
May be there is the other method?
All this code is in MyMethod which I execute in NSOperationQueue:
operation = [[NSInvocationOperation alloc] initWithTarget:self selector:#selector(MyMethod) object:nil];
[operationQueue addOperation:operation];
EDIT: image sizes are not big - from 50 to 100 kbyte
EDIT: can image file extension affect to downloading process?
You can try this:
NSURL *url = [NSURL URLWithString:recipeImageFullPath];
NSData *data = [NSData alloc] initWithContentsOfURL:url];
Please try to test it:
NSError *requestError;
NSURLResponse *urlResponse = nil;
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&requestError];
/* Return Value
The downloaded data for the URL request. Returns nil if a connection could not be created or if the download fails.
*/
if (responseData == nil) {
// Check for problems
if (requestError != nil) {
...
}
}
else {
// Data was received.. continue processing
}

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