Difficulty receiving JSON from GET request using NSURLConnection - ios

Question

I'm having a hard time trying to receive JSON form a NSURLConnection request. Can anybody offer any advice? I can't understand why the JSON does not appear
EDIT: When I append the endpoint /books to the end of the url string I get this JSON response: " json NSDictionary * 0 key/value pairs. " Does this mean that there is nothing in the server?
-(void)makeLibraryRequests
{
NSURL *url = [NSURL URLWithString:#"http://prolific-interview.herokuapp.com/54bexxxxxxxxxxxxxxxxaa56"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; //;]cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:20.0f];
[request setHTTPMethod:#"GET"];
// This is actually how jQuery works. If you don't tell it what to do with the result, it uses the Content-type to detect what to do with it.
[request setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
//[request setValue:#"application/json; charset=UTF-8" forHTTPHeaderField:#"Content-Type"];
[NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue alloc]init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
//parse data here!!
NSError *jsonError;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&jsonError];
if (json) {
//NSArray *allBooks = [json objectForKey:#"books"];
//create your MutableArray here
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData];
});
}
else{
NSLog(#"error occured %#", jsonError);
NSString *serverResponse = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"\n\nError:\n%#\n\nServer Response:\n%#\n\nCrash:", jsonError.description, serverResponse);
//[NSException raise:#"Invalid Data" format:#"Unable to process web server response."];
}
}];
}

Answer 1

As YiPing pointed out, you must provide the books end point. But you won't have anything there until you first post a book.
NSDictionary *params = #{#"author": #"Diego Torres Milano",
#"categories" : #"android,testing",
#"title": #"Android Application Testing Guide",
#"publisher": #"Packt Publishing",
#"lastCheckedOutBy": #"Joe"};
NSURL *url = [NSURL URLWithString:#"http://prolific-interview.herokuapp.com/54bexxxxxxxxxxxxxaa56/books/"]; // your id removed for security's sake ... put it back in
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:#"POST"];
[request setValue:#"application/json" forHTTPHeaderField:#"Accept"];
[request setValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
NSError *encodeError;
NSData *body = [NSJSONSerialization dataWithJSONObject:params options:0 error:&encodeError];
NSAssert(body, #"JSON encode failed: %#", encodeError);
request.HTTPBody = body;
So, first POST a book using a request like the above, then your original GET (assuming you add the end point) will now return a result.

Answer 2

Add some endpoints to your URL
try this:
http://prolific-interview.herokuapp.com/54bexxxxxxxxxxxxxxxxaa56/books/