NSMutableDictionary setobject: forkey: crashes with unrecognised selector message - ios

Question

For the below code snippet:
error occurs at setObject: forKey:
response <--is an NSDictionary
if(response){
NSMutableArray *lifeArray = [[NSMutableArray alloc] init];
NSMutableDictionary *responseDict = [[NSMutableDictionary alloc] init];
responseDict = (NSMutableDictionary *)[response mutableCopy];
[responseDict setObject:#"life" forKey:#"label"]; <-- Error here
}
Note that variable responseDict is NSMutableDictionary since copied via mutableCopy.
Error message:
2014-11-12 12:16:08.534 Lifetape[84381:508759] -[__NSCFArray setObject:forKey:]: unrecognized selector sent to instance 0x7a296700
2014-11-12 12:16:08.536 Lifetape[84381:508759] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFArray setObject:forKey:]: unrecognized selector sent to instance 0x7a296700'
*** First throw call stack:
(
0 CoreFoundation 0x028fbdf6 __exceptionPreprocess + 182
1 libobjc.A.dylib 0x02557a97 objc_exception_throw + 44
2 CoreFoundation 0x02903a75 -[NSObject(NSObject) doesNotRecognizeSelector:] + 277
3 CoreFoundation 0x0284c9c7 ___forwarding___ + 1047
4 CoreFoundation 0x0284c58e _CF_forwarding_prep_0 + 14
5 Lifetape 0x000dfb83 __50-[LTTimeLineTableViewController getTimeIntervals:]_block_invoke + 307
6 Lifetape 0x0014cedb -[MethodInvoker maybeInvokeCallback] + 395
7 Lifetape 0x0014d19f -[MethodInvoker receiveResultWithError:andResult:] + 399
8 Lifetape 0x00143e38 -[MeteorClient(Connection) livedata_result:] + 1544
9 Lifetape 0x00138674 __54-[MeteorClient(Connection) initConnectionWithOptions:]_block_invoke_3 + 2660
10 Lifetape 0x0014b2b5 -[MeteorClient didReceiveMessage:] + 197
11 Lifetape 0x0014eb7d -[ObjectiveDDP webSocket:didReceiveMessage:] + 269
12 Lifetape 0x0015d986 __30-[SRWebSocket _handleMessage:]_block_invoke + 102
13 libdispatch.dylib 0x031e941a _dispatch_call_block_and_release + 15
14 libdispatch.dylib 0x03209e1f _dispatch_client_callout + 14
15 libdispatch.dylib 0x031f0981 _dispatch_main_queue_callback_4CF + 610
16 CoreFoundation 0x02855f3e __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
17 CoreFoundation 0x02814d40 __CFRunLoopRun + 2256
18 CoreFoundation 0x028141ab CFRunLoopRunSpecific + 443
19 CoreFoundation 0x02813fdb CFRunLoopRunInMode + 123
20 GraphicsServices 0x051a524f GSEventRunModal + 192
21 GraphicsServices 0x051a508c GSEventRun + 104
22 UIKit 0x00f41e16 UIApplicationMain + 1526
23 Lifetape 0x000ce36d main + 141
24 libdyld.dylib 0x03235ac9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

Here your response dictionary is a NSDictionary type collection so it does not have any selector like setObject, that's why it is giving you this error use
if(response && [response isKindOfClass:[NSDictionary class]]){
NSMutableArray *lifeArray = [[NSMutableArray alloc] init];
NSMutableDictionary *responseDict = [NSMutableDictionary dictionaryWithDictionary:response];
[responseDict setObject:#"life" forKey:#"label"];
}
and it will work but make sure response is your dictionary type object. as the error you have posted clearly says that your response is an array not a dictionary.

Answer 2

Your response looks like NSArray class so try below code.
if([response isKindOfClass:[NSArray Class]]){
NSLog(#"Array");
}
else if([response isKindOfClass:[NSDictionary Class]]){
NSLog(#"Dictionary");
}
Now manage your code as per log.