[ios] Xcode - How to fix 'NSUnknownKeyException', reason: … this class is not key value coding-compliant for the key X" error?

I'm trying to link a UILabel with an IBOutlet created in my class.

My application is crashing with the following error.

What does this mean?

How can I fix it?

*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIViewController 0x6e36ae0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key XXX.'

This error is something else!

Here is how i Fixed it. I'm using xcode Version 6.1.1 and using swift. I got this error every time my app tried to perform a segue to jump to the next screen. Here what I did.

1. Checked that the button was connected to the right action.(This wasn't the problem, but still good to check)
2. Check that the button does not have any additional actions or outlets that you may have created by mistake. (This wasn't the problem, but still good to check)
3. Check the logs and make sure that all the buttons in the NEXT SCREEN have the correct actions, and if there are any segues, make sure that they have a unique identifier. (This was the problem)
   • One of the segues did not have a unique identifier
   • One of the buttons had an action and two outlets that I created by mistake.
   • Delete any additional outlets and make sure that you the segues to the next screen have unique identifiers.

Cheers,

This also happens to me when an UI label or other UI element is referenced by two variables in the view controller class and I delete one of the variable.

In my case it was that an IBOutlet's property name in a ViewController.m was changed, but the one in Storyboard was not. Reintroducing the IBOutlet into the ViewController.m per ctrl-drag solved the problem. I have also noticed a way to find such "orphane" IBOutlets in XCode: (look at the image) the ones that are not "orphaned" have concentric circles instead of line numbers.

I had the same issue.This happened with my project because I changed my product name but in interface builder I had the old name as Module, this leads to crash so be sure to check all the xib module name also has been changed or not.

If it is an iPhone only app, not a universal one, make sure the following field is empty:

Targets > Summary > iPhone/iPod Deployment Info > Main Interface

If you specify an xib there it crashes.

Check if you have stray Referencing Outlets by selecting the offending object in the Storyboard/xib interface and opening the Connections Inspector (View->Utilities->Show Connections Inspector). If you do remove the unwanted connections and you should be good to go.

My fix was similar to Gerard Grundy's. In creating a custom UITableViewCell using an XIB, I had mistakenly applied the Custom Class name to the File's Owner instead of to the UITableViewCell. Applying the class to the UITableViewCell on the canvas and connecting my IBOutlet properties to it solved the issue.

My problem started after i changed the Target name.

My own custom UI classes had the Module name set to the old target name.

I changed the target name to the new one and it works fine now.

I had this problem with swift classes after upgrading to xcode7. Solved it by using the @objc directive:

@objc(XXXViewController) class XXXViewController

In my case,

[[NSBundle mainBundle] loadNibNamed:@"NameOfTheSubviewNibFile" owner:self options:nil]

was the reason.

replacing this with initWithNibName, resolved.

I had the same issue when I was using the main storyboard as the launch screen file. I guess if you are using a storyboard as the launch screen file, it shouldn't be connected to the view controller as it won't have been loaded yet.

This has already happened to me twice.

The solution was remaking the whole storyboard since I copied it from another one (because it was almost the same)

I encountered this error that occurred on all outlets in a custom class I had created for a table view prototype cell. The outlets were all correctly connected to the storyboard, and the Class field was correctly named in the identity inspector for the prototype cell.

Deleting and recreating the outlets did not work. Cleaning the build did not work. What finally worked was to change the Class in the storyboard identity inspector to the default UITableViewCell, hit Enter, then change it back to the name of my custom class afterwards. For some reason, this worked.

That might be the case of referencing a component from Xib Interface that you have renamed or delete. Re-referencing works for me.

I also had this problem, it was due to renaming a view by creating a new outlet to it. Your might have the old connection outlet in the storyboard.

What you need to do is to remove the old outlet from the storyboard.

1. Goto the storyboard.
2. Click "Show Code Review" button (the one the <- -> sign on it, just left of the show/hide navigator).
3. Search for the "connections" tag.
4. Look for the "outlet" tag within the "connections" tag with the "property" attribute set to the name you are getting in the Exception.
5. Remove that outlet tag.
6. Hit "Command + B", Enjoy!

In my case, this was caused by referencing the wrong Nib:

BMTester *viewController = [[BMTester alloc] initWithNibName:@"WrongNibName" bundle:nil];

Another one cause of this situation is that you declare this property implemented as @dynamic, but class can not find it in parent class.

I had the same problem and while TechZen's answer may indeed be amazing I found it hard to apply to my situation.

Eventually I resolved the issue by linking the label via the Controller listed under Objects (highlighted in the image below) rather then via the File Owner.

Hope this helps.

I had to delete the app from the simulator/iPhone to get rid of this error.

"this class is not key value coding-compliant for the key" I know its a bit late but my answer is different so I thinks it needs to be posted, I was pushing the second controller in wrong way, Here is sample

Wrong Way to Push Controller

UIViewController* controller = [[UIViewController
 alloc]initWithNibName:@"TempViewController" bundle:nil];
         [self.navigationController pushViewController:controller animated:true];

Correct way

TempViewController* controller = [[TempViewController
 alloc]initWithNibName:@"TempViewController" bundle:nil];
         [self.navigationController pushViewController:controller animated:true];

I did not found any answer like above so may be it can help some one having same issue

Sometimes this has to do with your "Inherit From Target" That value has to be set. With single target apps you can just select Inherit From Target. If you have more then one target select the desired target.

I deleted the property from the header file. I couldn't find any reference to it but the debug error was still referencing it. I found that the nib file still had a reference to it. I deleted the block that referenced it and everything was fixed.

In Project Navigator,

Find the Nib (xib) file. Right click and View Source. I deleted the the following full section

<object class="IBConnectionRecord">
    <object class="IBCocoaTouchOutletConnection" key="connection">
        <string key="label">DeleteLabel</string>
        <reference key="source" ref="372490531"/>
        <reference key="destination" ref="774585933"/>
    </object>
    <int key="connectionID">20</int>
</object>

I had this problem too. I had copied a view with an IBOutlet from one xib file to another xib file. And even though I had removed the old reference and create a new reference, this error was still occurring.

I ended up restarting xcode to fix this problem.

I had the same symptom. The root cause was that the "Target Membership" for my source file was not set to the correct target. I assume that means my class wouldn't get built and included in my app.

To correct it:

1. Highlight your .m file.
2. In the right pane, select the File Inspector.
3. Under the "Target Membership" section, make sure the appropriate build target is checked.

Hope this helps somebody out there.

I resolved this problem by doing 2 things:

1. Fixed Class reference of the view:

2. Reimported all Outlets:

This problem also happens if you want to design a small subview in a separate XIB file in Interface Builder, and in IB you set it to the same class as the parent view.

If you then show it like this:

UIViewController *vc = [[UIViewController alloc] initWithNibName:@"NameOfTheSubviewNibFile" bundle:nil];
[self.view addSubview:vc.view];

The view will appear, but if it's got IBOutlets connected to its File Owner, you'll get the error message. So, this should work instead:

1. In your the parent view's code, declare an IBOutlet UIView *mySubview to reference the view in the subview's nib file
2. In the subview's nib file, connect the File Owner to the view, and set it to mySubview
3. show it by doing:

[[NSBundle mainBundle] loadNibNamed:@"NameOfTheSubviewNibFile" owner:self options:nil]
[self.view addSubview:mySubview];

and you will be fine!

I found another possibility that may cause the issue.

When using "initWithNibName" method with the wrong xib name, it will lead to this kind of crash too.

Such as you choose to change a xib file's name, and then foget to change the name used in "initWithNibName" method to the same name.

This error indicates that an already connected Interface Builder object is removed/renamed in its owner's source (File's Owner).

Control-click on the Files's Owner in the Interface Builder if you see a exclamation mark you need to fix that.

In the picture below you can see that "aRemovedView" has an exclamation mark on its right, that's because I removed the IBOutlet view object while it was already connected in the IB.

This gives the following error: Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key aRemovedView.'

Really stupid mistake with me. So I decided to share here, hope this will help another people like me.

I have another submodule in my project, and I name a new class with same name with another class in main module, my new class NOT have xib file(100% by code), but another class in main module have xib file. I think Xcode linked wrong the new class with the xib file in main module.

That the reason for crash with message:

this class is not key value coding-compliant for the key tableView.

Same issue presented. My solution was to put the correct storyboard value in the Main Storyboard drop down. I had renamed mainstoryboard.storyboard, but not reset the deployment info.

Another "not compliant" issue I found was when I managed to have two copies of a class for some reason.

I was adding keys to the wrong copy. Interface Builder still saw the keys and let me hook up to them, but at runtime it was using the other copy of the class that didn't have the new keys.

To find which was the "right" copy I used XCode's cmd-click on the class name elsewhere to jump to the correct copy, then I killed off the bad unused copies (after bringing over my edits from the un-used copy first).

Moral of the story: duplicate class files are bad.

I had exact same error message and thanks (!!) to Kira from http://www.idev101.com I was able to solve the challenge. I only found her site after googling and stacking over all these threads. I'm now posting here for the next one that comes to StackOverFlow and has the same challenge I had since that person will most likely come to this thread over Google.

I realized, that I wrongly made this:

UIViewController *deviceViewController = [[UIViewController alloc] initWithNibName:@"DeviceViewController" bundle:nil];

Instead of THIS:

DeviceViewController *deviceViewController = [[DeviceViewController alloc] initWithNibName:@"DeviceViewController" bundle:nil];

Where

DeviceViewController

Was the name of my Class also known as

DeviceViewController.h 
DeviceViewController.m

You'll have to

"import DeviceViewController.h"

in your implementation (.m File) where you want to call e.g. another UIViewController.

I am absolutely not sorry if I am only stating the obvious for beginners like me and may get down votes as this is not exactly related to the question but I was searching 4 (?!?) hours straight now for the answer to these error message. If I can spare this to 1 or 2 people that'd be great :)

PS: For those interested in how the code continues for loading the other UIViewController:

    [self presentViewController:deviceViewController animated:YES completion:nil];

I had the same kind of problem. I created a tableviewCell in a XIB file and was getting that kind of error. My problem was that I defined the "File's Owner" class to be my cell view controller. I just took it out and set the cell's class (on the xib file click the border of the cell, go to the third tab on the right panel and where it says class chose your view controller).

Also try cleaning your code.

Along with other issues that you can see in other answers. The way I created this error for myself was that I started a project from scratch and begin by deleting the initial scene of my storyboard and then pasted a scene from another project into my storyboard.

There is no problem in doing that. You only need to add an entry point of your storyboard i.e. check the is initial View Controller on which ever view controller you like. Otherwise it will be a gray scene and throw you an error.

It can come from the fact that you have control dragged and created an outlet or action, and forgot to delete it. Even if you deleted the code, or even if you have made enough cmd+Z, you'll need to go in the connection inspector of your storyboard and see if the action or outlet you created is still here or not.

I ran into the same problem for a different reason: I was using the main storyboard as the launch screen file. I guess if you are using a storyboard as the launch screen file, it shouldn't be connected to the view controller as it won't have been loaded yet.

You may have a bad connection in your xib.

I've had this error many times. While TechZen's answer is absolutely right in this case, another common cause is when you change the name of a IBOutlet property in your .h/.m which you've already connected up to File's Owner in the nib.

From your nib:

1. Select the object in IB and go to the 'Connections Inspector'.

2. Under 'Referencing Outlets' make sure that your object isn't still connected to the old property name... if it is, click the small 'x' to delete the reference and build again.

   

Another common cause if you are using Storyboard, your UIButton might have more then one assignings (Solution is almost the same as for nib):

1. Open your storyboard and right click the UIButton

2. You will see that there is more than one assign/ref to this button. Remove one of the "Main..." greyed windows with the small "x":

   

The cause of my trouble, was that I duplicated a storyboard file (outside of Xcode if I recall correctly), then all view controllers in the duplicated file had same object-ID as in the original file. The remedy is to copy-pasted the view controllers, and they will then get a new object-ID. You can see the object-ID in the Identity Inspector.

This happens to me when my view controller originally had an .xib file, but now is created programmatically.

Even though I have deleted the .xib file from this project. The users iPhone/iPad may contain an .xib files for this viewcontroller.

Attempting to load an .xib file usually causes this crash:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIViewController 0x18afe0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key welcomeLabel.'

Solution when creating it programmatically may be this:

-(void)loadView {
    // Ensure that we don't load an .xib file for this viewcontroller
    self.view = [UIView new];
}

I had this happen when i had a UIView linked into a storyboard and connected IBOutlet like:

@property (strong, nonatomic) IBOutlet UIView *someView

but later on, i made the UIView into a custom class but forgot to change the class name of this IBOutlet defined above. its a strange error because if the custom view has no subviews it doesnt complain, but as soon as there are subviews it shows the error stated in the question but on one of the subviews and not the outer UIView where the problem actually exists. had me deleting and readding all the subviews trying to find the problem, when in fact had nothing to do with the subviews

I got the same problem. I did resetting the simulator. Removing and adding button control. and finally made a clean. :) Thanks to stack overflow. Some how my code became ok and starting working.

It could mean you're trying to use a sort descriptor without an atsign at the beginning. As in:

[array valueForKeyPath:@"distinctUnionOfObjects.self"]

Which must actually be:

[array valueForKeyPath:@"@distinctUnionOfObjects.self"]

Another tricky case:

In IB added ViewController to storyboard, deleted its view and set Custom Class to "MyViewController" so view is instantiated from MyViewController.xib

Specifying Storyboard ID the same "MyViewController" causes exception.

Changing Storyboard ID to some different name resolves the issue.

I was getting this error with storyboards. The above solution didn't seem to be the problem so I ended up deleting the view controller and adding it back in again (and of course reconnecting the segue and reassigning the class) which fixed it. I don't know what it really was, but I had renamed the associated view controller class shortly before this started, so maybe that had hosed something.

I had the same error in yet another slightly different form:

In interface builder, I have a navigation controller with a custom subcontroller. The class name of this was set correctly, however the NIB name (select subcontroller, go to Attributes Inspector) was set to the wrong file (basically to one of a different target). Resetting this to the correct filename solved the issue.

Looking over the other answers it seems like there are a lot of things that can cause this error. Here is one more.

If you

• have a custom view
• added an @IBInspectable property
• and then later deleted it

Then you may also get an error similar to

Failed to set (xxx) user defined inspected property on [Your Custom View] ...: this class is not key value coding-compliant for the key [xxx].

The solution is to delete the the old property.

Open the Identity inspector for your class, select the property name under User Defined Runtime Attributes, and press the minus button (-).

To add to this epic saga of a thread...

My view controller had an attribution above it: @objc(TheNameOfMyViewController)

This made all the Outlets crash with "not key value compliant" error for each Outlet. This was only an issue on IOS12 and below. It worked fine on iOS 13.

Removing that modifier fixed this problem. All the outlets are working fine now.

Make sure you add the custom class' (even empty) implementation in the .m file like:

@implementation MySubclass
@end

In my case, I had added a ViewController to the storyboard, but I didn't assign it a Storyboard ID in the designer. Once I gave it an ID, it worked.

using Xamarin/Visual Studio 2015.

I had a similar problem for a project that has two targets (with their own MainWindow XIB). The fundamental issue that caused this error for me was that the UIViewController class wasn't included in the second project's resource list. I.e. interface builder allowed me to specify it in MainWindow.xib, but at runtime the system couldn't locate the class.

I.e. cmd-click on the UIViewController class in question and double-check that it's included in the 'Targets' tab.

You may need to delete the outlet , recreate it by drawing form IB to .H file.

This was happening to me only when debugging on a device (iPhone). The iOS Simulator was working OK. Doing a "Product->Clean" from Xcode seemed to solve the problem, but I have no idea why.

In my case it was the module that was specified to the wrong target. Simply deleting the module name and checking Inherit Module from target did the trick.

Did you leave your picker object unconnected?

lol 54 answers and not one of them is my solution. Talk about a common error.

In my case it was because I had a picker object on my VC and had not set an outlet and action for it.

I often leave buttons etc unconnected when I am just looking to see how the layout looks. But it seems you cannot do this for a picker.

You may have outlets to UI Element but not IBOutlet property in .h File

For all UI element in Connection Attribute check outlets and it corresponding property in .h header file.

May be missing one or more property entry in .h file.

Just to add to this, because I was getting this error as well. Going through all these answers most seem to apply to working with the UI and storyboard stuff. I know the original poster did seem to be working with the UI but when searching for possible reasons for this error mostly all questions lead back to this question with those others being closed as duplicates or simply having issues with connecting things in a storyboard so I will add my solution.

I was working on coding a web service in Swift 2. I had built all the needed proxy objects and stubs. As I looped through the returned XML I was dynamically instantiating my objects, which all came from NSObject and using setValue:forKey on them. Every time setValue:forKey tried to set a property it blew up with this error.

I had a switch statement for each type I was dealing with (e.g. Bool?, CShort?, String?) and for each XML node I went through and checked what the type was on the object and then converted the value to that type and attempted to set it with setValue:forKey.

Eventually I started commenting out all these setValue:forKey lines and found that my default switch statement case did work for String?.

I finally figured out that you can't use optional swift types with setValue:forKey unless they have a direct mapping to an Objective-C type like String? or NSNumber?. I ended up changing all CShort? types to NSNumber? since that has a direct mapping. For Bool? in my case it was fine for me to just use Bool and initialize it to false. Others may not have that luxury.

Anyway what a headache that was so hopefully this helps someone else who has a similar problem and keeps getting redirected to this question and saying to themselves, "I am not doing anything in UI!!".

So lastly to reiterate one more time Key-Value Coding does not work with optionals. Below I ended up finding somewhere but I forget where so to whoever posted this I apologize and would give credit if I remembered where I found this but it saved my life:

You cannot use KVC on an Optional Int property, because KVC is Cocoa / Objective-C, and Objective-C cannot see an Optional Int - it is not bridged to Objective-C. Objective-C can only see types that are bridged to Objective-C:

class types that are derived from NSObject

class types that are exposed with @objc

Swift structs that are bridged

1. You only need to specify IBOutlet once, the IBOutlet label your ivar is unnecessary.
2. Are you instantiating your NIB using your UIViewController? At some point you should be calling [SecondView initWithNibName:@"yourNibName" bundle:nil];

Usually when this happens to me, @TechZen's answer does the trick. Yesterday, however, I spent an embarrassingly long time mucking with storyboard connections only to discover that the problem was in my code.

I have a custom view controller that handles various layouts in my storyboard, but one of the layouts needed a special label not used by the others. So I created a subclass like so:

@interface MyViewControllerSubclass : MyViewController

Then I added a private property in MyViewControllerSubclass.m:

@interface MyViewController ()
@property (weak, nonatomic) IBOutlet UILabel *crashesApp;
@end

Xcode happily allowed me to connect this IBOutlet, yet every time the view would load, the app would crash with the old "not key-value compliant for the key 'chrashesApp'".

The solution, which is semi-obvious in retrospect, was to change the private category to use the correct name, i.e., that of the subclass:

@interface MyViewControllerSubclass ()
@property (weak, nonatomic) IBOutlet UILabel *noMoreCrashing;
@end

I got the same error when I manually loaded a view from a nib. It turns out that I had forgotten to set the view's owner.

For e.g. If you load a view in the following way,

 let view = Bundle.main.loadNibNamed("MyNibFileName",
                                 owner: nil,
                                 options: nil)?.first as! UIView

and then add an IBOutlet, the IBOutlet can't be referenced and the application will crash with the above error.

Fix: Assign an owner for the view.

 let view = Bundle.main.loadNibNamed("MyNibFileName",
                                 owner: self,
                                 options: nil)?.first as! UIView

"Module" property of View Controller in the Identity Inspector might be different than what you expected. Also make sure that new classes are added to your target list.

I encounter the same error log when dealing with my tableview cell. I found that my UILabels have duplicated referencing outlets(you could check it out in the reference inspector) to both the file's owner and my cell's class. Things get well when I delete the reference to the file's owner.

I had this problem with storyboard and swift class for ui view controller. Solved it by using the @objc directive:

@objc(MyViewController) class MyViewController

I had this error when I was trying to implement a custom ViewCell for a table. When I highlighted View controller for the XIB and connected to the elements in the CellView caused the error " this class is not key value coding-compliant for the key" once I deleted these it got rid of the error.

Delete the connections in the below image.

Just make sure that you only have the connections with the Table View Cell. To check click on table view cell and in INSPECTOR look for your connections.

in my case it was an error in the storyboard source code, follow these steps:

1. first open your story board as source code
2. search for <connections>
3. remove unwanted connections

For example:

<connections>
    <outlet property="mapPostsView" destination="4EV-NK-Bhn" id="ubM-Z6-mwl"/>
    <outlet property="mapView" destination="kx6-TV-oQg" id="4wY-jv-Ih6"/>
    <outlet property="sidebarButton" destination="6UH-BZ-60q" id="8Yz-5G-HpY"/>
</connections>

As you see, these are connections between your code variables' names and the storyboard layout xml tags ;)

I had the same issue, and the cause was due to specifying a Module in Interface Builder (as opposed to leaving it blank). So, when I was using either a different module than the one I set, the app would crash :S ... hope this helps someone else, as my issue was not due to a broken or out-of-date outlet!

If you have a custom UIViewController subclass with IBOutlets that are causing problems the only set of steps I found to actually get rid of the error were

.1 Change the class to UIViewController

.2 Disconnect all the outlets (they will all have the yellow warning triangle now) - it may be enough just to disconnect the problematic outlet(s).

.3 Do all the standard steps - ??K, delete Derived Data (, prayer mats, worry beads)

.4 Launch the app - go to the problematic scene.

.5 Kill the app, go back to Interface Builder change the class back to your custom class name.

.6 Reconnect your outlets.

Launch the app & this will normally have cleared up the key-value compliance issues.

Just pay attention if you're trying to observe a value that doesn't exist.

This happened to me simply as I was observing the "Text" property of a text field when I was supposed to be observing the "text" property instead.

I remember having a similar problem in the past, I solved it by changing the line:

_vicMain = [[UIViewController alloc] initWithNibName:@"vicMainScreen" bundle:nil];

into:

#include "vicLogin_iPad.h"       // This is the H file of the class holding the code for
                                 // processing all the IBOUtlets for the Login screen
.
.
.

_vicMain = [[vicLogin_iPad alloc] initWithNibName:@"vicMainScreen" bundle:nil];

Notice that I was initially declaring UIViewController to init my _vicMain, after using a pop-up window on top, I realised that both are using the same UIViewController.

By:

1) INCLUDing your class (of the sub-view), along with the same module that is doing the above _vicMain (which is a view controller object/variable) i.e. it's "vicLogin_iPad.h" in my case , and:

2) Use the your custom constructor to declare the object (i.e. instead of "xxx = [UIViewController alloc] ... ", you use "xxx = [vicLogin_iPad alloc] ... " instead.

the problem is resolved.

I hope this helps as it was a pain to pinpoint with the lack of details from the error message...

Regards Heider Sati

I just had this issue in my duplicated project and solved by checking 2 places:

1- Make sure you have the .m file in the list -> Project - Build Phases - Compile Sources
2- After that, go to interface builder (probably this is an error occures with only IB) and unlink all properties, labels, images, etc... Then re-link all. I have realized that I've removed an attribute but it was still linked in IB.

Hope it works for some.

In my case. I didn't have missing outlets in xib-files after merging.

Shift + Command + K

solved my problem. I cleaned my project and rebuilt.

Sometimes swift file are not added or removed from target, go to target-->Build setting --> compile Sources --> see if any required swift class file is missing or not . In my case Application was crashing due to swift source file not present in compile.