Why does this error occur? - iphone

Question

i am parsing the data from web service.After parsing the few records it gives this error.Somebody please the tell me what the reason behind this error?
[NSXMLParser length]: unrecognized selector sent to instance 0x6e6d340
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSXMLParser length]: unrecognized selector sent to instance 0x6e6d340'
*** Call stack at first throw:
(
0 CoreFoundation 0x026c4919 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x028125de objc_exception_throw + 47
2 CoreFoundation 0x026c642b -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x02636116 ___forwarding___ + 966
4 CoreFoundation 0x02635cd2 _CF_forwarding_prep_0 + 50
5 Foundation 0x001053e9 -[NSXMLParser parse] + 104
6 SexOffenders 0x00009c30 -[UserProfileVC connectionDidFinishLoading:] + 565
7 Foundation 0x0006e666 -[NSURLConnection(NSURLConnectionReallyInternal) sendDidFinishLoading] + 108
8 Foundation 0x0006e5bf _NSURLConnectionDidFinishLoading + 133
9 CFNetwork 0x02c569f1 _ZN19URLConnectionClient23_clientDidFinishLoadingEPNS_26ClientConnectionEventQueueE + 285
10 CFNetwork 0x02d1fc72 _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 402
11 CFNetwork 0x02d200ea _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 1546
12 CFNetwork 0x02d200ea _ZN19URLConnectionClient26ClientConnectionEventQueue33processAllEventsAndConsumePayloadEP20XConnectionEventInfoI12XClientEvent18XClientEventParamsEl + 1546
13 CFNetwork 0x02c4bdfe _ZN19URLConnectionClient13processEventsEv + 100
14 CFNetwork 0x02c4bc95 _ZN17MultiplexerSource7performEv + 247
15 CoreFoundation 0x026a5d7f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
16 CoreFoundation 0x026041dd __CFRunLoopDoSources0 + 333
17 CoreFoundation 0x026037c6 __CFRunLoopRun + 470
18 CoreFoundation 0x02603280 CFRunLoopRunSpecific + 208
19 CoreFoundation 0x026031a1 CFRunLoopRunInMode + 97
20 GraphicsServices 0x02f292c8 GSEventRunModal + 217
21 GraphicsServices 0x02f2938d GSEventRun + 115
22 UIKit 0x002dab58 UIApplicationMain + 1160
23 SexOffenders 0x00002198 main + 102
24 SexOffenders 0x00002129 start + 53
)
terminate called after throwing an instance of 'NSException'

Answer 1

'-[NSXMLParser length]: unrecognized selector sent to instance 0x6e6d340
this shows you are calling a function which is not a member function of NSXMLParser class.
actually in your code you are calling any method which can not be invoke on the obeject of NSXMLParser class.
chechk by debugging pointer.

Answer 2

I just suffered from this same issue. For me the problem was caused by this line of code:
operation.responseSerializer = [AFXMLParserResponseSerializer serializer];
This serialised the responseObject I was passing into the parser to XML but the parser expects an NSData object. Simply getting rid of that line solved the problem.

Answer 3

I also faced the similar problem.
Fixed by changing my line
self.xmlParser = [[NSXMLParser alloc] initWithData:data];
to
self.xmlParser = (NSXMLParser *)responseObject;
I found my solution from this blog
Raywanderlick Blog
Explanation for Error
This configuration of [AFXMLParserResponseSerializer serializer] already return an initialized object and I was initializing it again using already initialized parser by considering it data object.
Commenting following line didn't work for me as suggested by #Hodson answer above and it doesn't make sense as this is default configuration of AFTNetworking library.
operation.responseSerializer = [AFXMLParserResponseSerializer serializer];