How to get values from a dictionary in iOS

Question

I am new to iOS. I created a login page and everything works fine. I used JSON for checking username and password and got the response from server in a dictionary format. I want to extract the values from the dictionary and check them in my program. The response which I get from the server is:

json: {
        error = 0;
        msg = "";
        value = {
                  user = false;
                };
      };

First I want to check if the value with the key error is 0 or 1. Then I want to check the value with the key user. I don't know how I should code to check it. Can anyone help?

The code which I tried is below:

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSString *respString = [[NSString alloc] initWithData:loginJSONData encoding:NSUTF8StringEncoding];

    SBJsonParser *objSBJSONParser = [[SBJsonParser alloc] init];

    NSDictionary *json = [[NSDictionary alloc] initWithDictionary:[objSBJsonParser objectWithString:respString]];

    NSLog(@"json: %@",json);

    NSString *error = [json objectForKey:@"error"];

    NSLog(@"error: %@", error);

    if ([error isEqualToString:@"o"])
    {
        NSLog(@"login successful");
    }
    else
    {
        NSLog(@"login fail");
    }
}

yes, i tried to do it using NSDictionary and how to programmatically get the value "false" — Saba Sayed, Nov 14 '13 at 05:20
Post the code (by updating your question) you tried so people can help. — rmaddy, Nov 14 '13 at 05:21
http://stackoverflow.com/questions/10368303/parsing-a-json-array-into-a-nsdictionary check it — square, Nov 14 '13 at 05:27
Why are you comparing `error` with the string `@"o"`? That's a lowercase O, not a zero. And `error` will be a number, not a string. — rmaddy, Nov 14 '13 at 05:31
You can try this code to get the user value NSDictionary *dict = [json objectForKey:@"value"]; NSLog(@"%@",[dict objectForKey:@"user"]); You can still optimize this code to make it in one line — denil, Nov 14 '13 at 08:35

score 18 · Answer 1 · edited Nov 12 '14 at 16:20

18

Using modern Objective-C, accessing things in arrays and dictionaries become easier.

You should use the following syntax:

id<NSObject> value = dictionary[@"key"];

Similarly,

id<NSObject> value = array[1]; // 1 is the index

Applying the above to the question:

NSString *error = json[@"error"];

NSDictionary *value = json[@"value"];

BOOL user = [json[@"value"][@"user"] boolValue];

As in the above line, nesting is allowed, but it is not a good practice.

edited Nov 12 '14 at 16:20

Abdurrahman Mubeen Ali

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answered Nov 14 '13 at 05:49

cream-corn

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i tried above code but its throwing exception. can u please tell how to code for user for getting the values "true" or "false". – Saba Sayed Nov 14 '13 at 06:37
so the first segment `json[@"value]` returns us the NSDictionaryObject containing the user attribute then accessing `json[@"value"][@"user"]` will return us the boolean as a NSNumber object (at least i think) then calling `BoolValue` on that will convert into a BOOL... I suspect that the exception is happening when we try to call `boolValue`, could you paste the exception? – cream-corn Nov 14 '13 at 06:43
[__NSDictionaryM boolValue]: unrecognized selector sent to instance 0x756a050 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryM boolValue]: unrecognized selector sent to instance 0x756a050' libc++abi.dylib: terminate called throwing an exception – Saba Sayed Nov 14 '13 at 06:57
Try these in isolation to see if the individual calls work; try `json[@"value"][@"user"]` and see what type the object is. – cream-corn Nov 14 '13 at 23:05

Inder Kumar Rathore · Answer 2 · 2013-11-14T05:41:41.583

5

NSNumber *error = [json objectForKey:@"error"];
if ([error intValue] == 0)
{
    NSLog(@"login successful");

    NSDictionary *value = [json objectForKey:@"value"];
    NSNumber *user = [value objectForKey:@"user"];
    if ([user boolValue])
    {
        NSLog(@"user == true");
    }
    else
    {
        NSLog(@"user == false");
    }
}
else
{
    NSLog(@"login failed");
}

edited Nov 14 '13 at 05:41

answered Nov 14 '13 at 05:30

Inder Kumar Rathore

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1

The code for `user` is incorrect. `json` does not have a `user` key. – rmaddy Nov 14 '13 at 05:32
Move the code to get the user inside the "then" portion of the `if` statement and you have the right answer. – rmaddy Nov 14 '13 at 05:41
@rmaddy I don't have exact idea where he wants to write the code to check `user` value but inside `if` it's the most appropriate. Thanks for the suggestion – Inder Kumar Rathore Nov 14 '13 at 05:44
I made the suggestion because that is what I thought the OP stated but after reading again I see that it is unclear. But it makes sense to only check the user if there is no error. – rmaddy Nov 14 '13 at 05:45

score 2 · Answer 3 · edited Feb 04 '19 at 06:05

2

The dictionaries that normally returning from the server will be as a key value pair. if you are looking for accessing these values that corresponds to a key, then these code may help you

NSString *varname = [[NSString alloc]initWithFormat:@"%@",[dictionaryname objectForKey:@"key"]];

edited Feb 04 '19 at 06:05

Nagarjun

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answered Dec 04 '14 at 07:16

SARATH SASI

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iPatel · Answer 4 · 2013-11-14T05:32:18.400

1

For get error value from your JSON Dictionary.

NSString *error = [myJSONDicName objectForKey:@"error"];

For get user value from your JSON Dictionary.

NSString *error = [[myJSONDicName objectForKey:@"value"] objectForKey:@"user"];

EDITED:

You just need to change In your

if ([error isEqualToString:@"o"])
                            _^_
                             |

change 'o' to '0'

edited Nov 14 '13 at 05:32

answered Nov 14 '13 at 05:21

iPatel

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Yes, the OP does. But the OP is incorrect. That's one of the reason the OP's code doesn't work. – rmaddy Nov 14 '13 at 05:37
@rmaddy - but in the case of OP.. he/she only need to check error is `0` or `1` then i think `isEqualToString` is work. – iPatel Nov 14 '13 at 05:39
But the code will crash since `NSNumber` doesn't have an `isEqualToString:` method. – rmaddy Nov 14 '13 at 05:40
@rmaddy - `NSNumber`??? sorry but OP got it as NSString so not need to use `NSNumber`.. – iPatel Nov 14 '13 at 05:41
As I said, the OP is wrong. Look at the JSON. The `0` is not in quotes, is not an `NSString`. – rmaddy Nov 14 '13 at 05:43

manujmv · Answer 5 · 2013-11-14T05:43:45.850

0

You can use the below code

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
   {
          NSString *respstring = [[NSString alloc]initWithData:loginJsonData encoding:NSUTF8StringEncoding];
          NSDictionary *dic = [responseString JSONValue];
         NSLog(@"%@",dic);
         NSNumber *error = [dic objectForKey:@"error"];
        if([error intValue] == 0)  {
           NSLog(@"login successful");
        }
        else
        {
            NSLog(@"login fail");
        }

        NSString *user = [value objectForKey:@"user"];
        BOOL userStatus = [user boolValue];
 }

edited Nov 14 '13 at 05:43

answered Nov 14 '13 at 05:33

manujmv

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The OP already has code for getting the dictionary from the JSON. That's not the question. – rmaddy Nov 14 '13 at 05:34
It still doesn't answer the question. Keep going. – rmaddy Nov 14 '13 at 05:36

How to get values from a dictionary in iOS

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