3rd rejection by Apple - developer cannot find a solution

First of all I want to greet the community since this is my first post.

I have been finding here helpful solutions to my problems for long but know the time has come to ask for your help.

I have to mention that I am not the developer of the app but the project manager running the project for a client. As the title says we have been rejected for the third time by Apple with the following reasoning:

We found that your app crashed on iPad running iOS 7.1.1 and iPhone 5s running iOS 7.1.2, which is not in compliance with the App Store Review Guidelines.

When we launch the app, permit location information and begin to fill out the form, the app crashes after we enter an age. When we re-launch the app, a white screen is displayed for a few moments, then the app crashes.

• on iPhone the app crashes when we select a new field to fill in on the registration page

This occurred when your app was used:

• On Wi-Fi

The developers working on the project after trying hard they seem to not be able to identify the problem so I am relying to any of you that can give us a helpful hand.

The latest crash log Apple sent us is the following

 {"name":"BancPost","bug_type":"109","os_version":"iPhone OS 7.1.2 (11D257)","bundleID":"com.arxnet.BancPost","version":"1.0 (1.0)","app_name":"BancPost"}
    Incident Identifier: F4F91032-C5FE-4E45-A68E-81E318D6DE12
    CrashReporter Key:   e095a4fb863515f7e479267e05e62cb887e1d9eb
    Hardware Model:      xxx
    Process:             BancPost [28176]
    Path:                /var/mobile/Applications/05876C8E-A2E5-4FD1-951E-B4AF34CB2B06/BancPost.app/BancPost
    Identifier:          com.arxnet.BancPost
    Version:             1.0 (1.0)
    Code Type:           ARM (Native)
    Parent Process:      launchd [1]

    Date/Time:           2014-08-05 12:47:49.822 -0700
    OS Version:          iOS 7.1.2 (11D257)
    Report Version:      104

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Triggered by Thread:  0

Last Exception Backtrace:
(0x2d54ef7e 0x381fccca 0x2d54eec0 0x2dedc7d6 0xb080a 0x386e482e 0x386e481a 0x386eb49a 0x2d51989c 0x2d518170 0x2d482eba 0x2d482c9e 0x323b665e 0x2fdcf148 0x86802 0x38709ab2)

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libsystem_kernel.dylib          0x387bf1f0 __pthread_kill + 8
1   libsystem_pthread.dylib         0x38829792 pthread_kill + 54
2   libsystem_c.dylib               0x3876ffd8 abort + 72
3   libc++abi.dylib                 0x37a9ecd2 abort_message + 70
4   libc++abi.dylib                 0x37ab76e0 default_terminate_handler() + 248
5   libobjc.A.dylib                 0x381fcf62 _objc_terminate() + 190
6   libc++abi.dylib                 0x37ab51c4 std::__terminate(void (*)()) + 76
7   libc++abi.dylib                 0x37ab4a18 __cxa_throw + 112
8   libobjc.A.dylib                 0x381fcd9e objc_exception_throw + 246
9   CoreFoundation                  0x2d54eec0 +[NSException raise:format:] + 100
10  Foundation                      0x2dedc7d6 +[NSJSONSerialization JSONObjectWithData:options:error:] + 62
11  BancPost                        0x000b080c 0x3b000 + 481292
12  libdispatch.dylib               0x386e4830 _dispatch_call_block_and_release + 8
13  libdispatch.dylib               0x386e481c _dispatch_client_callout + 20
14  libdispatch.dylib               0x386eb49a _dispatch_main_queue_callback_4CF$VARIANT$mp + 274
15  CoreFoundation                  0x2d51989c __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 4
16  CoreFoundation                  0x2d518170 __CFRunLoopRun + 1296
17  CoreFoundation                  0x2d482eba CFRunLoopRunSpecific + 518
18  CoreFoundation                  0x2d482c9e CFRunLoopRunInMode + 102
19  GraphicsServices                0x323b665e GSEventRunModal + 134
20  UIKit                           0x2fdcf148 UIApplicationMain + 1132
21  BancPost                        0x00086802 0x3b000 + 309250
22  libdyld.dylib                   0x38709ab4 start + 0

Thread 1 name:  Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0   libsystem_kernel.dylib          0x387ac808 kevent64 + 24
1   libdispatch.dylib               0x386ee078 _dispatch_mgr_invoke + 228
2   libdispatch.dylib               0x386eddfe _dispatch_mgr_thread$VARIANT$mp + 34

Thread 2:
0   libsystem_kernel.dylib          0x387bfc70 __workq_kernreturn + 8
1   libsystem_pthread.dylib         0x38826bda _pthread_wqthread + 306
2   libsystem_pthread.dylib         0x38826a94 start_wqthread + 4

Thread 3:
0   libsystem_kernel.dylib          0x387bfc70 __workq_kernreturn + 8
1   libsystem_pthread.dylib         0x38826bda _pthread_wqthread + 306
2   libsystem_pthread.dylib         0x38826a94 start_wqthread + 4

Thread 4:
0   libsystem_kernel.dylib          0x387aca58 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x387ac854 mach_msg + 44
2   CoreFoundation                  0x2d519846 __CFRunLoopServiceMachPort + 150
3   CoreFoundation                  0x2d517f6c __CFRunLoopRun + 780
4   CoreFoundation                  0x2d482eba CFRunLoopRunSpecific + 518
5   CoreFoundation                  0x2d482c9e CFRunLoopRunInMode + 102
6   Foundation                      0x2de761e6 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 250
7   Foundation                      0x2dec709c -[NSRunLoop(NSRunLoop) run] + 76
8   BancPost                        0x000c00b4 0x3b000 + 544948
9   Foundation                      0x2df38a5a __NSThread__main__ + 1058
10  libsystem_pthread.dylib         0x38828916 _pthread_body + 138
11  libsystem_pthread.dylib         0x38828886 _pthread_start + 98
12  libsystem_pthread.dylib         0x38826aa0 thread_start + 4

Thread 5:
0   libsystem_kernel.dylib          0x387bfc70 __workq_kernreturn + 8
1   libsystem_pthread.dylib         0x38826bda _pthread_wqthread + 306
2   libsystem_pthread.dylib         0x38826a94 start_wqthread + 4

Thread 6 name:  com.apple.NSURLConnectionLoader
Thread 6:
0   libsystem_kernel.dylib          0x387aca58 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x387ac854 mach_msg + 44
2   CoreFoundation                  0x2d519846 __CFRunLoopServiceMachPort + 150
3   CoreFoundation                  0x2d517f6c __CFRunLoopRun + 780
4   CoreFoundation                  0x2d482eba CFRunLoopRunSpecific + 518
5   CoreFoundation                  0x2d482c9e CFRunLoopRunInMode + 102
6   Foundation                      0x2dec3082 +[NSURLConnection(Loader) _resourceLoadLoop:] + 314
7   Foundation                      0x2df38a5a __NSThread__main__ + 1058
8   libsystem_pthread.dylib         0x38828916 _pthread_body + 138
9   libsystem_pthread.dylib         0x38828886 _pthread_start + 98
10  libsystem_pthread.dylib         0x38826aa0 thread_start + 4

Thread 7 name:  AFNetworking
Thread 7:
0   libsystem_kernel.dylib          0x387aca58 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x387ac854 mach_msg + 44
2   CoreFoundation                  0x2d519846 __CFRunLoopServiceMachPort + 150
3   CoreFoundation                  0x2d517f6c __CFRunLoopRun + 780
4   CoreFoundation                  0x2d482eba CFRunLoopRunSpecific + 518
5   CoreFoundation                  0x2d482c9e CFRunLoopRunInMode + 102
6   Foundation                      0x2de761e6 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 250
7   Foundation                      0x2dec709c -[NSRunLoop(NSRunLoop) run] + 76
8   BancPost                        0x001276f6 0x3b000 + 968438
9   Foundation                      0x2df38a5a __NSThread__main__ + 1058
10  libsystem_pthread.dylib         0x38828916 _pthread_body + 138
11  libsystem_pthread.dylib         0x38828886 _pthread_start + 98
12  libsystem_pthread.dylib         0x38826aa0 thread_start + 4

Thread 8:
0   libsystem_kernel.dylib          0x387bfc70 __workq_kernreturn + 8
1   libsystem_pthread.dylib         0x38826bda _pthread_wqthread + 306
2   libsystem_pthread.dylib         0x38826a94 start_wqthread + 4

Thread 9 name:  com.apple.CFSocket.private
Thread 9:
0   libsystem_kernel.dylib          0x387bf434 __select + 20
1   CoreFoundation                  0x2d51d708 __CFSocketManager + 480
2   libsystem_pthread.dylib         0x38828916 _pthread_body + 138
3   libsystem_pthread.dylib         0x38828886 _pthread_start + 98
4   libsystem_pthread.dylib         0x38826aa0 thread_start + 4

Thread 0 crashed with ARM Thread State (32-bit):
    r0: 0x00000000    r1: 0x00000000      r2: 0x00000000      r3: 0x00002060
    r4: 0x00000006    r5: 0x3a7b518c      r6: 0x00000000      r7: 0x27dc6fe4
    r8: 0x16ea0900    r9: 0x00000001     r10: 0x27dc7e78     r11: 0x002807c0
    ip: 0x00000148    sp: 0x27dc6fd8      lr: 0x38829797      pc: 0x387bf1f0
  cpsr: 0x00000010

Thanks

Look at the line:

NSJSONSerialization JSONObjectWithData:options:error:

It suggests that the app crashes while trying to create an object from JSON data.