title: Terminating app due to uncaught exception 'NSInvalidArgumentException',
body: <p>i hav this error. can anyone help me...</p>
  
  <pre><code>Call stack at first throw:
  (
      0   CoreFoundation                      0x00dc25a9 __exceptionPreprocess + 185
      1   libobjc.A.dylib                     0x00f16313 objc_exception_throw + 44
      2   CoreFoundation                      0x00dc40bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
      3   CoreFoundation                      0x00d33966 ___forwarding___ + 966
      4   CoreFoundation                      0x00d33522 _CF_forwarding_prep_0 + 50
      5   UIKit                               0x002b24fd -[UIApplication sendAction:to:from:forEvent:] + 119
      6   UIKit                               0x00342799 -[UIControl sendAction:to:forEvent:] + 67
      7   UIKit                               0x00344c2b -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527
      8   UIKit                               0x003437d8 -[UIControl touchesEnded:withEvent:] + 458
      9   UIKit                               0x002d6ded -[UIWindow _sendTouchesForEvent:] + 567
      10  UIKit                               0x002b7c37 -[UIApplication sendEvent:] + 447
      11  UIKit                               0x002bcf2e _UIApplicationHandleEvent + 7576
      12  GraphicsServices                    0x0171a992 PurpleEventCallback + 1550
      13  CoreFoundation                      0x00da3944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
      14  CoreFoundation                      0x00d03cf7 __CFRunLoopDoSource1 + 215
      15  CoreFoundation                      0x00d00f83 __CFRunLoopRun + 979
      16  CoreFoundation                      0x00d00840 CFRunLoopRunSpecific + 208
      17  CoreFoundation                      0x00d00761 CFRunLoopRunInMode + 97
      18  GraphicsServices                    0x017191c4 GSEventRunModal + 217
      19  GraphicsServices                    0x01719289 GSEventRun + 115
      20  UIKit                               0x002c0c93 UIApplicationMain + 1160
      21  BasicNavigation                     0x00001ea0 main + 102
      22  BasicNavigation                     0x00001e31 start + 53
  )
  terminate called after throwing an instance of 'NSException'
  Program received signal:  “SIGABRT”.
  (gdb) 
  </code></pre>