ios - Getting error on clicking button in swift -

i newbie ios development , started learning basic stuffs in swift. getting error while try run basic coding practising auto layout. below exceptions occurs while try open dialog on clicking button. posting sample code reference

the exception getting follows:

<nslayoutconstraint:0x79e84ca0 v:[uilabel:0x79e82b40'sadadsfsadfsd']-(90)-[_uilayoutguide:0x79e84610]>  make symbolic breakpoint @ uiviewalertforunsatisfiableconstraints catch in debugger. methods in uiconstraintbasedlayoutdebugging category on uiview listed in <uikit/uiview.h> may helpful. 2015-10-01 00:04:18.833 firstdemo[6922:355986] -[firstdemo.viewcontroller showsomething]: unrecognized selector sent instance 0x79e80210 2015-10-01 00:04:18.836 firstdemo[6922:355986] *** terminating app due uncaught exception 'nsinvalidargumentexception', reason: '-[firstdemo.viewcontroller showsomething]: unrecognized selector sent instance 0x79e80210' *** first throw call stack: (     0   corefoundation                      0x0025aa94 __exceptionpreprocess + 180     1   libobjc.a.dylib                     0x01e5ce02 objc_exception_throw + 50     2   corefoundation                      0x00263de3 -[nsobject(nsobject) doesnotrecognizeselector:] + 275     3   corefoundation                      0x001a1e3d ___forwarding___ + 1037     4   corefoundation                      0x001a1a0e _cf_forwarding_prep_0 + 14     5   libobjc.a.dylib                     0x01e710b5 -[nsobject performselector:withobject:withobject:] + 84     6   uikit                               0x00a3dc40 -[uiapplication sendaction:to:from:forevent:] + 118     7   uikit                               0x00a3dbbf -[uiapplication sendaction:totarget:fromsender:forevent:] + 64     8   uikit                               0x00bd38fc -[uicontrol sendaction:to:forevent:] + 79     9   uikit                               0x00bd3c7c -[uicontrol _sendactionsforevents:withevent:] + 408     10  uikit                               0x00bd2c87 -[uicontrol touchesended:withevent:] + 714     11  uikit                               0x00ab4eb8 -[uiwindow _sendtouchesforevent:] + 1095     12  uikit                               0x00ab5da4 -[uiwindow sendevent:] + 1118     13  uikit                               0x00a5e9b3 -[uiapplication sendevent:] + 266     14  uikit                               0x00a35903 _uiapplicationhandleeventqueue + 7327     15  corefoundation                      0x00174e7f __cfrunloop_is_calling_out_to_a_source0_perform_function__ + 15     16  corefoundation                      0x0016ab0b __cfrunloopdosources0 + 523     17  corefoundation                      0x00169f28 __cfrunlooprun + 1032     18  corefoundation                      0x00169866 cfrunlooprunspecific + 470     19  corefoundation                      0x0016967b cfrunloopruninmode + 123     20  graphicsservices                    0x045fa664 gseventrunmodal + 192     21  graphicsservices                    0x045fa4a1 gseventrun + 104     22  uikit                               0x00a3bcc1 uiapplicationmain + 160     23  firstdemo                           0x000784fc main + 140     24  libdyld.dylib                       0x028cda21 start + 1 ) libc++abi.dylib: terminating uncaught exception of type nsexception 

viewcontroller.swift

import uikit  class viewcontroller: uiviewcontroller {      override func viewdidload() {         super.viewdidload()         // additional setup after loading view, typically nib.     }      override func didreceivememorywarning() {         super.didreceivememorywarning()         // dispose of resources can recreated.     }       @ibaction func showmessage(){          let alertcontroller = uialertcontroller(title:"success",message:"awesome done",preferredstyle:uialertcontrollerstyle.alert)         alertcontroller.addaction(uialertaction(title: "ok", style: uialertactionstyle.default, handler: nil))          self.presentviewcontroller(alertcontroller, animated: true, completion: nil)     } } 

please me. kindly text me if question not clear. in advance

so in interface builder created ibaction attached button. looks named 'showsomething' , renamed 'showmessage'.

to fix bug either can change name of method 'showsomething', or you'll have go interface builder, select button, , check outlet connections (the button on upper right that's circle arrow in it).

you'll see old outlet connection showsomething, delete , reconnect button new function 'showmessage'.