unrecognized selector sent to instance error in Objective-C

Question

I created a button and added an action for it  but as soon as it invoked  I got this error   - NSCFDictionary numberButtonClick    unrecognized selector sent to instance  0x3d03ac0 2010-03-16 22 23 58 811  Money 8056 207      Terminating app  due to uncaught exception   NSInvalidArgumentException   reason      - NSCFDictionary numberButtonClick     unrecognized selector sent to instance 0x3d03ac0    This is my code   -  id initWithNibName  NSString   nibNameOrNil bundle  NSBundle   nibBundleOrNil       if  self    super initWithNibName nibNameOrNil bundle nibBundleOrNil             UIButton  numberButton    UIButton buttonWithType UIButtonTypeCustom                   numberButton frame   CGRectMake 10  435  46  38            numberButton setImage  UIImage imageNamed   one png   forState UIControlStateNormal            numberButton addTarget self action  selector numberButtonClick   forControlEvents UIControlEventTouchUpInside            self view addSubview  numberButton          return self     - IBAction numberButtonClick  id sender      NSLog   ---

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My case was  collectionView inside a View  I was trying to add the gestureRecognizer in a config   method that I have wrote by myself  After some workaround i ve found that  I have simply to move the code inside the awakeFromNib     override func awakeFromNib           other code     let longPressGesture   UILongPressGestureRecognizer target  self  action   selector handleLongGesture gesture        self collectionView addGestureRecognizer longPressGesture      And it worked well   I hope that this can help someone

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This was the top Google answer for this issue  but I had a different cause result - I thought I d add in my two cents in case others stumble across this problem    I had a similar issue just this morning   I found that if you right click the UI item giving you the issue  you can see what connections have been created   In my case I had a button wired up to two actions   I deleted the actions from the right-click menu and rewired them up and my problem was fixed   So make sure you actions are wired up right

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In my case the function was not expecting an argument but the button was configured to send one causing the error  To fix this I had to rewire the event handler    Here is my function           Notice it contains no arguments    Here is an image of my button configuration  right click on the button to view it        Notice there are 3 event handlers      To fix this I had to remove each of the event items since one of them was sending a reference to itself to the enterPressed function  To remove these items I clicked on the little x icon next to the name of each item until there were no items shown       Next I had to reconnect the button to the event  To do this hold down the Control key and then drag a line from the button to the action  It should say  Connect Action   Note  I had to restart XCode for this to work for some reason  otherwise it only let me insert actions  aka create a new action  above or below the function      You should now have a single event handler wired to the button event that passes no arguments       This answer compliments the answer by  Leonard Challis which you should read as well

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In my case    My protocol definition       protocol MyProtocol  -  void Method    end   and I forgot implements the delegate methods   hope it could help someone

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Another possible solution   Add  -ObjC  to your linker arguments   Full explanation is here  Objective-C categories in static library  I think the gist is  if the category is defined in a library you are statically linking with  the linker isn t smart enough to link in category methods   The flag above makes the linker link in all objective C classes and categories  not just ones it thinks it needs to based on analyzing your source    Please feel free to tune or correct that answer   I m knew to linked languages  so I m just parroting here

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Basics  Dynamic Invocation The objective C is a dynamic language which invokes methods by looking at runtime for methods in classes  For example  if there is Class A including method DoSomething arg1  arg2   If you try to call the method using correct arguments on an object of Class A everything will work fine  However  if the arguments are not passes properly  for example  you called the method with one argument only then the the run-time will treat this as a method call for a different method  Eventually  run-time will fail to find the method  DoSomething with one argument  and will through this exception  quot unrecognized selector sent to instance quot   Solution Please check what signature for  selector is expected  Usually it is  as you described in the code - IBAction numberButtonClick  id sender

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How to debug    unrecognized selector send to instance    In most of the cases Xcode do not take us to the exact line where this issue happen  When app crash you won   t see the line of code that caused this rather you will be taken to App delegate class  with error output something following   UITableViewCellContentView image   unrecognized selector sent to instance  or    NSDictionaryI objectAtIndex   unrecognized selector sent to instance  or     Terminating app due to uncaught exception  NSInvalidArgumentException   reason   - TestApp MyViewController viewDidLoad    unrecognized selector sent to instance 0xDABCDD   How to find line of code causing this  Go to breakpoint navigator  Click         option  click    Exception Breakpoint     An new widget like following will apear   Add following condition block  - NSObject NSObject  doesNotRecognizeSelector     You can also put breakpoint for all exception  Now run your code again  this time  breakpoint will trigger when this exception occurs  WRITTEN BY  Prafulla Singh Full explanition  https   prafullkumar77 medium com how-to-debug-unrecognized-selector-send-to-instance-402473bc23d

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My problem and solution was different and I thought I should post it here so that future readers can save their head from banging to the wall    I was allocating different xib to same UIVIewController and even after searching everywhere I couldn t find how to correct it  Then I checked my AppDelegate where I was calling initWithNibName and can see that while copying the code  I changed the xib name  but forgot to change UIViewController class  So if none of the solution works for you  check your initWithNibName method

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I had a similar problem  but for me the solution was slightly different  In my case  I used a Category to extend an existing class  UIImage for some resizing capabilities - see this howto in case you re interested  and forgot to add the   m file to the build target  Stupid error  but not always obvious when it happens where to look  I thought it s worth sharing

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I got the issue too  and at last I found the solution for my issue I was builded the controller s UI in storyboard   but the controller s UI did not relate its control to code  I use this code to init vc       UIStoryboard  sb    UIStoryboard storyboardWithName   Me  bundle nil        sb instantiateViewControllerWithIdentifier   HeaderViewController      This code above will cause the issue  and after I changed the init code to this below  I resolved the problem   HeaderViewController  head vc     HeaderViewController alloc  init

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I had the same error and I discovered the following   When you use the code   self refreshControl addTarget self action  selector yourRefreshMethod   forControlEvents UIControlEventValueChanged     You may think it s looking for the selector   -  void yourRefreshMethod       your code here      But it s actually looking for the selector   -  void yourRefreshMethod  id sender       your code here      That selector doesn t exist  so you get the crash   You can change the selector to receive  id sender in order to solve the error   But what if you have other functions that call the refresh function without providing a sender  You need one function that works for both  Easy solution is to add another function   -  void yourRefreshMethodWithSender  id sender       self yourRefreshMethod       And then modify the refresh pulldown code to call that selector instead    self refreshControl addTarget self action  selector yourRefreshMethodWithSender   forControlEvents UIControlEventValueChanged     I m also doing the Stanford iOS course on an older Mac that can t be upgraded to the newest version of Mac OSX  So I m still building for iOS 6 1  and this solved the problem for me

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The most obvious cause of this  included for completeness  is improperly casting a pointer and calling a method of the wrong class   NSArray  array     NSArray alloc  init     NSDictionary  array objectForKey  key      array is not a dictionary  hence exception

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It looks like you re not memory managing the view controller properly and it is being deallocated at some point - which causes the numberButtonClicked  method to be sent to another object that is now occupying the memory that the view controller was previously occupying     Make sure you re properly retaining releasing your view controller

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I had the same issue  The problem for me was that one button had two Action methods  What I did was create a first action method for my button and then deleted it in the view controller  but forgot to disconnect the connection in the main storyboard in the connection inspector  So when I added a second action method  there were now two action methods for one button  which caused the error

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It can happen when you do not assign the ViewController to the ViewControllerScene in  the InterfaceBuilder  So the ViewController m is not connected to any scene

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This happened to my because accidentally erase the     IBAction func      inside my UIViewcontroller class code  so in the Storyboard was created the Reference Outlet  but at runtime there was any function to process it    The solution was to delete the Outlet reference inside the property inspector and then recreate it dragging with command key to the class code   Hope it helps

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I had this after switching from Swift 2 to Swift 3  The description below is specific  but you can see the generic case of it covers a lot of possible errors   I had a method called delete in my subclass of SKNode    func delete thing  SomeType     There is already a method delete on UIResponder  but my method  unintentionally  overloaded it  so it was working fine  Upgrading to Swift 3 changed it to   func delete   thing  SomeType     Still working  But then I decided to Swift3ify it and made the parameter mandatory   func delete thing  SomeType    which would have worked fine if I remembered to update the caller  but I didn t so now the caller is calling the no-parameter-name delete method in UIResponder with the wrong type of arguments   This can obviously happen with any of the long list of of standard methods on SKNode  and probably UIView  that take Any as an argument and so will pass the compilation phase but then fall-over when called

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This can also happen if you don t set the  Class  of the view in interface builder

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Yet another slightly different solution case    I am using Xamarin and MvvmCross and I was trying to bind the UIButton to a ViewModel  I had the UIButton wired up to an Outlet and a TouchUpInside   When Binding I only use the Outlet   set Bind  somethingOutlet  For   TouchUpInside   To vm   gt  vm Something     All I had to do was remove the action  TouchUpInside  connection in XCode and that solved it    P S  I guess this is in its base all related to the previous answers and to  Chris Kaminski in particular  but I hope this helps someone     Cheers

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For those getting here via Google like I did  which probably pertains more to Xcode 4 2  iOS 5  more  what with ARC  I had the same error  unrecognized selector sent to instance   In my case I had a UIButton s target action set up to pass itself as the sender parameter  but later realised I didn t need it and removed that in code  So  something like   -  IBAction buttonPressed  UIButton   sender     Was changed to   -  IBAction buttonPressed     Right clicking the UIButton in question showed that the Touch Up Inside event was associated with the view controllers buttonPressed  method  Removing this and reassigning it to the modified method worked a treat

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I also had the same issue   I deleted my uibutton in my storyboard and recreated it    now everything works fine

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I think you should use the void  instead of the IBAction in return type  because you defined a button programmatically

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I m currently learning iOS development and going through the  Beginning iOS6 Development  book by aPress   I was getting the same error in Chapter 10 Storyboards   It took me two days to figure it out but found out I accidentally set the TableView cell s tag to 1 when I shouldn t have    For anyone else doing this book and receive a similar error I hope this helps      I really hope future errors in my code are easier to find  hahaha   The debug error did nothing to push me in the right direction to figuring it out  or at least I m too new to understand the debugger  lol

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In my case I was using a UIWebView and I passed a NSString in the second parameter instead of a NSURL  So I suspect that wrong class types passed to a functions can cause this error

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OK LISTED UP  I m VERY new to XCODE  had this problem  and figured it out  So if that sounds like you  here s the answer  When you control   click and drag the button to your ViewController file  so you can code it   you will be asked to fill out the properties of the button in a popup  The bottom of the popup  under Type  will say  quot SENDER quot   YOU NEED TO CHANGE IT TO  quot NONE quot

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OK  I have to chip in here  The OP dynamically created the button  I had a similar issue and the answer  after hours of hunting  is so simple it made me sick   When using   action  selector xxxButtonClick    or  as in my case   action NSSelectorFromString   NSString alloc  initWithFormat     BtnTui    name lowercaseString     If you place a colon at the end of the string - it will pass the sender  If you do not place the colon at the end of the string it will not  and the receiver will get an error if it expects one  It is easy to miss the colon if you are dynamically creating the event name   The receiver code options look like this   -  void doneBtnTui  id sender     NSLog   Done Button - with sender       or -  void doneBtnTui     NSLog   Done Button - no sender        As usual  it is always the obvious answer that gets missed

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And now mine  I had the button linked to a method which accessed another button s parameter and that worked great BUT as soon I tried to do something with the button itself  I got a crash  While compiling  no error has been displayed   Solution   I failed to link the button to the file s owner  So if anyone here is as stupid as me  try this

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On my case I solved the problem after 2 hours    The sender  a tabBar item  wasn t having any Referencing Outlet  So it was pointing nowhere   Juste create a referencing outlet corresponding to your function   Hope this could help you guys

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In my case  I was using NSNotificationCenter and was attempting to use a selector that took no arguments  but was adding a colon   Removing the colon fixed the problem   When using a selector name  don t use a trailing colon if there are no arguments   If there s one argument  use one trailing colon   If there are more than one argument  you must name them along with a trailing colon for each argument   See Adam Rosenfield s answer here  Selectors in Objective-C

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I got this issue trying some old format code in Swift3    let swipeRight   UISwipeGestureRecognizer target  self  action   selector self respond     changing the action  respond   to action   selector self respond  fixed the issue for me

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I m replying to Leonard Challis  since I was also taking the Stanford iOS class C193P  as was user  oli206    Terminating app due to uncaught exception  NSInvalidArgumentException   reason    The problem was that I had the  Enter  button on the calculator connected twice and a friend pointed out that doing an inspection of the button in the Storyboard showed that 2 entries were on the  Touch Up Inside  attributes when I right clicked on the  Enter  button   Erasing one of the two  Touch Up Inside   Sent Events  solved the problem   This showed that the problem is triggered  for the C193P video class on the Calculator Walkthrough on Assignment 1  as 2 sent events  one of which was causing the exception

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Happened to me because of conflicting constraint arguments

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I had this problem with a Swift project where I m creating the buttons dynamically  Problem code   var trashBarButtonItem  UIBarButtonItem       return UIBarButtonItem barButtonSystemItem   Add  target  self  action   newButtonClicked      func newButtonClicked barButtonItem  UIBarButtonItem        NSLog  A bar button item on the default toolbar was clicked    barButtonItem         The solution was to add a full colon     after the action  e g   var trashBarButtonItem  UIBarButtonItem           return UIBarButtonItem barButtonSystemItem   Add  target  self  action   newButtonClicked               func newButtonClicked barButtonItem  UIBarButtonItem            NSLog  A bar button item on the default toolbar was clicked    barButtonItem             Full example here  https   developer apple com library content samplecode UICatalog Listings Swift UIKitCatalog DefaultToolbarViewController swift html

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Including my share  I got stuck on this for a while  until I realized I ve created a project with ARC Automatic counting reference  disabled  A quick set to YES on that option solved my issue

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Another reason solution to add to the list  This one is caused by iOS6 0  and or bad programming   In older versions the selector would match if the parameter types matched  but in iOS 6 0 I got crashes in previously working code where the name of the parameter wasn t correct   I was doing something like    objectName methodName   somestring  lat latValue lng lngValue     but in the definition  both  h and  m  I had   viod  methodName  NSString    latitude  double latitude longitude  double longitude    This worked fine on iOS5 but not on 6  even the exact same build deployed to different devices   I don t get why the compiler coudn t tell me this  anyway - problem soled

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This also might happen when you want to set a property from a ControllerA to a public property inside a custom ControllerB class and you haven t set the  Custom Class  inside the identity inspector in storyboards yet

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For me  it was a leftover connection created in interfacebuilder bij ctrl-dragging  The name of the broken connection was in the error-log      Terminating app due to uncaught exception  NSInvalidArgumentException   reason   - NameOfYourApp NameOfYourClass nameOfCorruptConnection    unrecognized selector sent to instance 0x7f97a48bb000    I had an action linked to a button  Pressing the button crashed the app because the Outlet no longer existed in my code  Searching for the name in the log led me to it in the storyboard  Deleted it  and the crash was gone

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Another really silly cause of this is having the selector defined in the interface  h  but  not in the implementation  m   p e  typo

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In my case  in iOS 13  I only had to implement the whole function and selector calling parts put in to main thread

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