How to get all values of one specific key from an array? - ios

Question

I am developing application using Objective C.
I am getting following array in the response from server side ( i'm using Get method of AFNetworking).
Response from server: `[{"name":"option1","profile_id":0,"profile_name":"option1"},{"name":"option2","profile_id":0,"profile_name":"option2"},{"name":"option3","profile_id":0,"profile_name":"option3"},{"name":"option4","profile_id":0,"profile_name":"option4"},{"name":"option5","profile_id":0,"profile_name":"option5"},{"name":"option6","profile_id":0,"profile_name":"option6"},{"name":"option7","profile_id":0,"profile_name":"option7"},{"name":"option8","profile_id":0,"profile_name":"option8"},{"name":"option9","profile_id":0,"profile_name":"option9"},{"name":"option10","profile_id":0,"profile_name":"option10"}]`
I want to separate values for the key name.
In short, i want output like:[option1,option2,option3,option4,option5,option6,option7,option8,option9,option10]
For that i tried like following way:
store that response in array (_arr). and then try to separate values for key name like following way,
NSArray *optionArray = [_arr valueForKey:#"name"];
NSLog(#"%#",optionArray);
but, unfortunately this is not working. Application crashes and gives following logs.
Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<__NSCFString 0x7abd0600> valueForUndefinedKey:]: this class is not key value coding-compliant for the key name.'
*** First throw call stack:
(
0 CoreFoundation 0x00ae2a14 __exceptionPreprocess + 180
1 libobjc.A.dylib 0x005a3e02 objc_exception_throw + 50
2 CoreFoundation 0x00ae2631 -[NSException raise] + 17
3 Foundation 0x00239098 -[NSObject(NSKeyValueCoding) valueForUndefinedKey:] + 282
4 Foundation 0x0017a798 _NSGetUsingKeyValueGetter + 105
5 Foundation 0x0017a727 -[NSObject(NSKeyValueCoding) valueForKey:] + 288
6 Foundation 0x001bac40 -[NSFunctionExpression expressionValueWithObject:context:] + 1079
7 Foundation 0x001ba739 -[NSComparisonPredicate evaluateWithObject:substitutionVariables:] + 290
8 Foundation 0x001ba60f -[NSPredicate evaluateWithObject:] + 48
9 Foundation 0x001ba593 _filterObjectsUsingPredicate + 437
10 Foundation 0x001ba360 -[NSArray(NSPredicateSupport) filteredArrayUsingPredicate:] + 314
11 Wellness_24x7 0x0008fbc4 __31-[ForthViewController Donating]_block_invoke + 564
12 Wellness_24x7 0x0006c097 __116-[AFHTTPSessionManager dataTaskWithHTTPMethod:URLString:parameters:uploadProgress:downloadProgress:success:failure:]_block_invoke97 + 231
13 Wellness_24x7 0x00080bd5 __72-[AFURLSessionManagerTaskDelegate URLSession:task:didCompleteWithError:]_block_invoke_2132 + 213
14 libdispatch.dylib 0x0330e377 _dispatch_call_block_and_release + 15
15 libdispatch.dylib 0x033319cd _dispatch_client_callout + 14
16 libdispatch.dylib 0x03316f90 _dispatch_main_queue_callback_4CF + 910
17 CoreFoundation 0x00a33fde __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
18 CoreFoundation 0x009f1cd4 __CFRunLoopRun + 2356
19 CoreFoundation 0x009f10e6 CFRunLoopRunSpecific + 470
20 CoreFoundation 0x009f0efb CFRunLoopRunInMode + 123
21 GraphicsServices 0x050c8664 GSEventRunModal + 192
22 GraphicsServices 0x050c84a1 GSEventRun + 104
23 UIKit 0x012ecbfa UIApplicationMain + 160
24 Wellness_24x7 0x0006905a main + 138
25 libdyld.dylib 0x0335ba21 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
Thank you in advance.

Answer 1

actually your JSON Response started with Array, so do like
NSArray *ResponseArray = [NSJSONSerialization JSONObjectWithData: data options: KNilOptions error: nil];
NSMutableArray *finalArray = [NSMutableArray array];
for (NSDictionary *temp in ResponseArray) {
[finalArray addObject:temp[#"name"]];
}
Choice-2 for AFNetworking
NSMutableArray *finalArray = [NSMutableArray array];
for (NSDictionary *temp in responseObject) {
[finalArray addObject:temp[#"name"]];
}

Answer 2

Try this
NSMutableArray *arrOptions = [NSMutableArray new];
for (int i=0; i<_arr.count; i++) {
[arrOptions addObject:[[_arr objectAtIndex:i] objectForKey:#"name"]];
}
here arrOptions will contain your desired output.

Answer 3

I can see that you are getting response in JSON format. So you can convert JSON into mutable containers like Dictionary and Arrays. In your case it is array of dictionaries.
NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutableContainers error: &e];
if(!jsonArray)
{
for(NSDictionary *dict in jsonArray)
{
NSLog(#"%#", dict valueForKey: #"name");
}
}

Answer 4

According to your JSON data below you need to store data using NSDictionary instead of an Array.
[{
"name": "option1",
"profile_id": 0,
"profile_name": "option1"
}, {
"name": "option2",
"profile_id": 0,
"profile_name": "option2"
}, {
"name": "option3",
"profile_id": 0,
"profile_name": "option3"
}, {
"name": "option4",
"profile_id": 0,
"profile_name": "option4"
}, {
"name": "option5",
"profile_id": 0,
"profile_name": "option5"
}, {
"name": "option6",
"profile_id": 0,
"profile_name": "option6"
}, {
"name": "option7",
"profile_id": 0,
"profile_name": "option7"
}, {
"name": "option8",
"profile_id": 0,
"profile_name": "option8"
}, {
"name": "option9",
"profile_id": 0,
"profile_name": "option9"
}, {
"name": "option10",
"profile_id": 0,
"profile_name": "option10"
}]
Get the data using dict like:
NSDictionary *jsonDataDict = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSArray *optionArray = [jsonDataDict valueForKey:#"name"];
Problem: you are trying to get data of name key and you storing whole JSON data inside an array.
Array doesn't contain key value pair use NSDictionary.

Answer 5

What you want to achieve and your thinking i can say you are on right track.
You have converted your response Data in NSDictionary but it must be an array.
NSArray *responseArray = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
this will convert your response to array and you can use
NSArray *optionArray = [responseArray valueForKey:#"name"];
This will lead to same result as answer from #Krishna Kumar but with this you will be able to avoid "for" loop.