CODEWITHSUNDEEP
iosobjective-cjsonparsing
iOSAddicted
iOSAddicted

Reputation: 389

Error getting JSON and trying to parse it [iOS]

I´ve been looking at this the entire day, looking other solutions but nothing, I can´t solve my problem.

I want to get the JSON of https://alpha-api.app.net/stream/0/posts/stream/global, parse it so I can extract the username and in a future other attributes like post, avatar... This is my viewDidLoad where I set up the connection with the URL and then I change it to NSData Object.

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL
                                                      URLWithString:@"https://alpha-api.app.net/stream/0/posts/stream/global"]];
NSData *response = [NSURLConnection sendSynchronousRequest:request
                                         returningResponse:nil error:nil];
NSError *jsonParsingError = nil;
NSArray *timeline= [NSJSONSerialization JSONObjectWithData:response
                                                          options:0 error:&jsonParsingError];
NSDictionary *user;
for(int i=0; i<[timeline count];i++)
{
    user = [timeline objectAtIndex:i];
    NSLog(@"Statuses: %@", [user objectForKey:@"username"]);
}

My program starts running and then it stops. I know when it stops(user = [timeline objectiAtIndex:i]) but I have no idea why... Another question: Would [user objectForKey:@"username"] be enough to extract the usernames?

Upvotes: 0

Views: 195

Answers (4)

nmock
nmock

Reputation: 1907

The timeline data is contained in a dictionary which can be accessed through the key "data". I would do something along the lines of: 

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL
                                                      URLWithString:@"https://alpha-api.app.net/stream/0/posts/stream/global"]];
NSData *response = [NSURLConnection sendSynchronousRequest:request
                                         returningResponse:nil error:nil];
NSError *jsonParsingError = nil;
NSDictionary *responseObject = [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError];
NSArray *timelineArray;

if (responseObject) {
    timelineArray = [responseObject objectForKey:@"data"];

    NSDictionary *user; // user data

    for (NSDictionary *status in timelineArray) {
        user = [status objectForKey:@"user"];

        NSLog(@"Status: %@", [status objectForKey:@"text"]);
        NSLog(@"Status by user: %@\n\n", [user objectForKey:@"username"]);
    }
}
}

Upvotes: 0

stackunderflow
stackunderflow

Reputation: 852

Your parsing logic is incorrectly assuming that timeline will be an NSArray when the structure of the data you are retrieving indicates that it will actually be an NSDictionary.

Upvotes: 0

Travis
Travis

Reputation: 3369

You're getting an error because the following line returns an NSDictionary, not an NSArray.

NSArray* timeline= [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError];

So it should be,

NSDictionary* timeline= [NSJSONSerialization JSONObjectWithData:response options:0 error:&jsonParsingError];

and your logic should be adjusted accordingly.

Upvotes: 1

Patrick Goley
Patrick Goley

Reputation: 5417

It's likely the web service is returning a JSON dictionary as opposed to an array. This would cause an unrecognized selector exception to throw on [timeline objectAtIndex:i]. Print out what the request returns in the debugger, and if it's a dictionary you'll need to find how to access the array you are expecting before iterating.

Upvotes: 0

Related Questions