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

Question

I have a problem in AppDelegate, when run the app I get this error:

  Terminating app due to uncaught exception 'NSUnknownKeyException', reason: 
  '[<UIApplication 0x856c820> setValue:forUndefinedKey:]:
   this class is not key value coding-compliant for the key view.'

This is the code of AppDelegate.h

#import <UIKit/UIKit.h>

@class ViewController;

@interface AppDelegate : UIResponder <UIApplicationDelegate>{

        //UINavigationController *navigationController;
 }

@property (strong, nonatomic) UIWindow *window;


@property (copy, nonatomic) ViewController * viewController;
@property (copy, nonatomic) UINavigationController * navigationController;



 @end

This is the code of AppDelegate.m

 #import "AppDelegate.h"

 #import "RootViewController.h"



  @implementation AppDelegate



  - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:  (NSDictionary *)launchOptions
   {
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

        RootViewController *rootMenu;


         if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
              rootMenu= [[RootViewController alloc]  initWithNibName:@"ViewController_iPhone" bundle:nil];
    } else {
              rootMenu = [[RootViewController alloc]initWithNibName:@"ViewController_iPad" bundle:nil];
  }


  self.navigationController =[[UINavigationController  alloc]initWithRootViewController:rootMenu];

  self.window.rootViewController = self.navigationController;

  [self.window makeKeyAndVisible];
   return YES;
 }

What can I do to resolve this error? I have rewritten the RootViewController, throwing in the trash the old one, but the problem remains the same.Thanks in advance

score 23 · Accepted Answer · answered Oct 04 '12 at 14:16

This usually happens when an Interface Builder or Storyboard connection hasn't properly been made. Sometimes you'll make a connection, and then delete the code that the connection was made to. Interface Builder still has a reference to the code, which causes the key/value compliant run time error. You can also get this error if you haven't assigned the proper class to a view controller. If you've written code for a particular view controller, be sure to set the class appropriately in Interface Builder for that View Controller.

If you right-click on items in IB to display the connections, there will be an "x" beside ones that are broken, so you can delete them. (Yeah, it should generate compile-time warnings instead.... maybe it does by now; do check your output.) — Rob Napier, Oct 04 '12 at 14:19

score 4 · Answer 2 · answered Mar 29 '15 at 22:12

I know this question is a bit old, but I was running into the same problem and the article below helped a lot. Basically it illustrates step-by-step how to fix the problem @bgolson described.

http://www.tech-recipes.com/rx/52021/how-do-i-fix-the-issue-this-class-is-not-key-value-coding-compliant-for-the-key-in-xcode-6/

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

2 Answers2