Getting the error in JSON parsing in iphone

Question

I am trying to pars the json data and display in table My JSON data is like this

{"isError":false,"ErrorMessage":"","Result":{"Count":4,"Data":[{"ContentID":"127_30_1309793318065","ContentTypeID":1,"UserCaption":"Gandhinagar(Kanjurmarg)","UserComment":"central\n","DateRecorded":"\/Date(1309793318000+0530)\/","Data":"","ShareType":true,"Views":0,"PlayTime},{},{},{}];};isError = 0;}

I am prasing like this

-(void)connectionDidFinishLoading:(NSURLConnection *)connection 
{      
    NSString *loginStatus = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding]; 
    NSLog(@"%@",loginStatus);  



    //this is for the getting the data from the server with help of JSON
    NSString *json_string = [[NSString alloc] initWithData:webData encoding:NSUTF8StringEncoding]; 
    NSDictionary *result = [json_string JSONValue];
    /
    //this for holding the Array value which come from the server 
    NSMutableArray *results = [[NSMutableArray alloc] init];
    for (int index = 0; index<[reviewsvalues count]; index++)
    {
        NSMutableDictionary * value = [reviewsvalues objectAtIndex:index];
        ReviewsResult * result = [[ReviewsResult alloc] init];
        result.User_Caption = [value objectForKey:@"UserCaption"];
        result.ContentType_Id = [value objectForKey:@"DateRecorded"];
        result.Average_Rating = [value objectForKey:@"AverageRating"];
        //OVER here MY APP GET CRASH 


    }


}

BUt it get crash and give error

[__NSCFDictionary objectAtIndex:]: unrecognized selector sent to instance

Parth Bhatt · Accepted Answer · 2011-10-05 07:24:54Z

2

The problem is simple.

reviewsvalues should be an NSDictionary and you should not be calling objectAtIndex: for the reviewsvalues.

Instead you should call valueForKey like

int count = [[reviewsvalues valueForKey:@"Count"] intValue];
NSArray *reviewsArray = [reviewsvalues valueForKey:@"Data"];
int count = [reviewsArray count];

cell.textLabel.text = [[reviewsArray objectAtIndex:indexPath.row] valueForKey:@"ContentID"];

Hope this helps you.

Please let me know if you want more help on this.

edited Oct 5, 2011 at 7:24

answered Oct 5, 2011 at 6:31

Parth Bhatt

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8 Comments

Harish Over a year ago

Yes you are right but done like this NSArray *reviewsArray = [reviewsvalues valueForKey:@"Data"]; but ? how can i set the value on to the cell and how can count row

Parth Bhatt Over a year ago

@Harish: reviewArray at each of its index contains a dictionary.

Harish Over a year ago

Can you come on line chat on stackchat

Parth Bhatt Over a year ago

@Harish: I have edited my answer and given more code on how you need to do this. Hope this helps. If you still have doubts then please let me know

Parth Bhatt Over a year ago

@Harish: Can you please wait for half an hour for participating in stackchat?

|

Kenny Winker · Accepted Answer · 2011-10-05 07:17:55Z

1

You set reviewsvalues = [result objectForKey:@"Result"];

Which means reviewsvalues is now an NSDictionary. "Result" is a dictionary, not an array:

{"Count":4,"Data":[...]}

NSDictionary doesn't respond to -objectAtIndex:, that's one of NSArray's methods.

You need another step:

NSArray *reviewsArray = [reviewsvalues objectForKey:@"Data"];

and while you are at it, you can use fast enumeration.

for (NSDictionary *review in reviewsArray) {
    ReviewsResult * result = [[ReviewsResult alloc] init];
    result.User_Caption = [review objectForKey:@"UserCaption"];
    result.ContentType_Id = [review objectForKey:@"DateRecorded"];
    result.Average_Rating = [review objectForKey:@"AverageRating"];
}

Edit: also, you should know that you've not coded this very defensively. What happens if the data isn't exactly as it is in your example? what happens if a value is missing, like "Data", or "Result"? Your app should be robust enough to not choke if something slightly unexpected happens.

edited Oct 5, 2011 at 7:17

answered Oct 5, 2011 at 5:34

Kenny Winker

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5 Comments

Harish Over a year ago

Than how can i handle when something slightly unexpected happens.

Harish Over a year ago

even it not work it get crash and give error Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary objectAtIndex:]:

Harish Over a year ago

at this link NSArray *reviewsArray = [reviewsvalues objectAtIndex:@"Data"]; it show me warning that passing argument 1 of 'objectAtIndex'makes integer from pointer without a cast

Kenny Winker Over a year ago

@harish Sorry, my mistake, should be objectForKey: not objectAtIndex:.

Kenny Winker Over a year ago

@harish have a look at the headers for NSDictionary, and NSArray... try to keep them separate in your mind. Be aware that you will mix them up (as I just did). That's what compiler warnings are for ;)

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