NSTaggedPointerString objectForKey in objective-c - ios

Question

when I try to fetch the result from the JSON result. It throws the following exception.
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSTaggedPointerString objectForKey:]: unrecognized selector sent to instance 0xa006449656c6f526'
My code.
NSString *responseStringWithEncoded = [[NSString alloc] initWithData: mutableData encoding:NSUTF8StringEncoding];
id jsonObjects = [NSJSONSerialization JSONObjectWithData:
mutableData options:NSJSONReadingMutableContainers error:nil];
for (NSDictionary *dataDict in jsonObjects) {
NSString *firstname = [dataDict objectForKey:#"FirstName"];
}
The above code throws an NSException.
My JSON response looks like this.
{
"IsExternal": 0,
"LoginId": 4,
"EmployeeId": 223,
"FirstName": "GharValueCA",
"RoleId": 4,
"LastName": null,
"Mobile": null,
"AgencyId": 100,
"BranchId": 74
}
Any help will be appreciated.

Answer 1

According to the definition of JSON, each JSON contains one object (which can be a collection type that contains other objects). In your case, your text starts with "{", so that's a dictionary. A single dictionary.
So NSJSONSerialization, when it reads that file, gives you back an NSDictionary containing values under keys like IsExternal, FirstName etc.
However, your code uses for( ... in ... ) on that dictionary (which, according to NSDictionary documentation, will iterate over the keys in the dictionary, which are strings), but then you treat those strings as if they were dictionaries again.
So instead of looping over the dictionary, you should just use the dictionary in jsonObjects directly, by calling something like -objectForKey: on it.

Answer 2

There is a misunderstanding:
jsonObjects is already the dictionary, assign the deserialized object immediately to dataDict.
NSDictionary *dataDict = [NSJSONSerialization JSONObjectWithData:mutableData
options:0
error:nil];
// mutableContainers in not needed to read the JSON
The enumerated objects are strings, numbers or <null>. You called objectForKey: on a string which caused the error.
Get the name directly (no loop)
NSString *firstname = dataDict[#"FirstName"];
or you can enumerate the dictionary
for (NSString *key in dataDict) {
NSLog(#"key:%# - value:%#", key, dict[key]);
}

Answer 3

You should call
[jsonObjects objectForKey:#"FirstName"];
to get the FirstName value.
Below lines of code returns you (probably) a NSDictionary, so this is the container that stores all of your json values.
id jsonObjects = [NSJSONSerialization JSONObjectWithData:
mutableData options:NSJSONReadingMutableContainers error:nil];

Answer 4

Try this code:
if ([jsonObjects isKindOfClass:[NSDictionary class]]) {
NSString *firstname = [jsonObjects objectForKey:#"FirstName"];
}
as your 'jsonObjects' is of generic type 'id' so just check that whether it is of NSDictionary type and then in if-block you can directly access it by objectForKey:

Answer 5

try this code, hope it help,
id jsonObjects = [NSJSONSerialization JSONObjectWithData:
mutableData options:NSJSONReadingMutableContainers error:nil];
if([jsonObjects respondsToSelector:#selector(objectForKey:)]){
NSString *firstname = [jsonObjects objectForKey:#"FirstName"];
}