JSON Data returned on NSURLConnection - arrays

Question

I have an iOS app where Users have to Register before using the app. I have created the UI in Storyboard and I am reading the Users details from the UITextfields. I then send the details to the Register API that sends back a JSON response. I am using NSURLConnection for the communication.
Here is the response I am receiving from the test URL - for testing purposes only:
{"username":"Hans","password":"Hans"}
However, when I try to read the password to make sure that the user doesn't already exists (again, just for testing purposes), I get nil returned for password value returned.
In my .h file I declare the Data and Connection:
#interface RegisterViewController : UIViewController <NSURLConnectionDataDelegate>
{
// Conform to the NSURLConnectionDelegate protocol and declare an instance variable to hold the response data
NSMutableData *buffer;
NSURLConnection *myNSURLConnection;
}
In my .m file, when someone clicks the REGISTER button, I create the request and start the connection as below. I am giving a dummy URL in example but the response I am receiving is:
{"username":"Hans","password":"Hans"}
- (IBAction)registerButtonClicked:(id)sender
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:#"http://myDummyURL/Login.php"]];
// Construct the JSON Data
NSDictionary *stringDataDictionary = #{#"firstname": firstname, #"lastname": lastname, #"email": email, #"password" : password, #"telephone" : telephone};
NSError *error;
NSData *requestBodyData = [NSJSONSerialization dataWithJSONObject:stringDataDictionary options:0 error:&error];
// Specify that it will be a POST request
[request setHTTPMethod:#"POST"];
// Set header fields
[request setValue:#"text/plain" forHTTPHeaderField:#"Accept"];
[request setValue:#"application/json; charset=utf-8" forHTTPHeaderField:#"Content-Type"];
//NSData *requestBodyData = [stringData dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:requestBodyData];
myNSURLConnection = [NSURLConnection connectionWithRequest:request delegate:self];
// Ensure the connection was created
if (myNSURLConnection)
{
// Initialize the buffer
buffer = [NSMutableData data];
// Start the request
[myNSURLConnection start];
}
}
The connection is created with no problem here.
In my .m file I implement the delegate methods and in connectionDidFinishLoading() I try and read the returned JSON. Below is the code I am using for this.
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// Dispatch off the main queue for JSON processing
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSError *error = nil;
NSString *jsonString = [[NSJSONSerialization JSONObjectWithData:buffer options:0 error:&error] description];
// Dispatch back to the main queue for UI
dispatch_async(dispatch_get_main_queue(), ^{
// Check for a JSON error
if (!error)
{
NSError *error = nil;
NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingMutableContainers error:&error];
NSDictionary *dictionary = [jsonArray objectAtIndex:0];
NSString *test = [dictionary objectForKey:#"password"];
NSLog(#"Test is: %#", test);
}
else
{
NSLog(#"JSON Error: %#", [error localizedDescription]);
}
// Stop animating the Progress HUD
});
});
}
From the log screen grab below you can see the jsonString returned has values but the jsonArray is always nil. The error reads: error NSError * domain: #"NSCocoaErrorDomain" - code: 3840 0x00007ff158498be0
Thanks in advance.

Answer 1

Your jsonString is in fact the NSDictionary object - created by NSJSONSerialization - you're looking for, there is no array. In a JSON string curly braces {} represent a dictionary and square brackets [] represent an array
Try this
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// Dispatch off the main queue for JSON processing
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSError *error = nil;
NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:buffer options:0 error:&error];
// Dispatch back to the main queue for UI
dispatch_async(dispatch_get_main_queue(), ^{
// Check for a JSON error
if (!error)
{
NSString *test = [dictionary objectForKey:#"password"];
NSLog(#"Test is: %#", test);
}
else
{
NSLog(#"JSON Error: %#", [error localizedDescription]);
}
// Stop animating the Progress HUD
});
});
}
Edit: I overlooked the description method at the end of the NSJSONSerialization line. Of course that must be deleted.

Answer 2

Your code has 2 issues:
You are converting JSON server response to NSString.
Your JSON data is indeed a NSDictionary.
This must fix your issue:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// Dispatch off the main queue for JSON processing
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSError *error = nil;
NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:buffer options:0 error:&error];
// Dispatch back to the main queue for UI
dispatch_async(dispatch_get_main_queue(), ^{
// Check for a JSON error
if (!error)
{
NSString *test = [dictionary objectForKey:#"password"];
NSLog(#"Test is: %#", test);
}
else
{
NSLog(#"JSON Error: %#", [error localizedDescription]);
}
// Stop animating the Progress HUD
});
});
}