unrecognized selector sent to instance

I am not sure what I am missing here. I went through the videos once and everything worked correctly. I started over to go through them a second time and I can’t get past the first part.

I have started from scratch five times and reinstalled Xcode just for good measure. Each time I get the same error:

Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘* -[UIApplication tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0×520760’

Here is my .m file code:

#import "Recipe4ViewController.h" 

@implementation Recipe4ViewController

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"recipeCell"];
    if(nil == cell) {
        cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:@"recipeCell"] autorelease];
    }
    if(indexPath.row == 0) {
        cell.text = @"Cherry Pie";
    } else if(indexPath.row == 1) {
        cell.text = @"Cake";
    } else if(indexPath.row == 2) {
        cell.text = @"Cookie";
    }
    return cell;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 3;
}

and here is the .h file:

@interface Recipe4ViewController : UIViewController <UITableViewDataSource> {
}
@end

Thanks for any help.

Craig

Check what the datasource for you tableview is set to. Everything in your code looks fine so my guess is that the datasource is set to a different object.

Good luck!

Thanks for following up Bill. So others may benefit from my mistake, here was the issue.
I was putting the table view into the MainWindow.xib.

Hi Craig,

So you had your table view’s datasource connected to the files owner in the MainWindow.xib file? And the file’s owner is the UIApplicaiton which does not conform to the UITableViewDatasource protocol.

Thanks for following up!

Hi Bill, I bought all your episodes. And they were really helpful in giving me Ramp up over iPhone Application Development. And by progressing through those I have got a slightly different version of the above problem.

I am creating Tab Bar Application using the template and in that I have attached the nib files in each of the Tab Bar item. Then Each of the view has been shown successfully.

Now I want to loads a table view in each of the tabs. I have created separate View Controller (VC) for each of the Tab and mentioned those VC name in each nib file’s File owner class attribute.
So the File Owner Class = FirstViewController
And from IB I have connected the datasource and delegates attributes of the view to my File Owner.

My View Controller declaration is below
@interface FirstViewController : UIViewController

and I have implemented the required method in FirstViewController.m similar to below

- (UITableViewCell )tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@”myCel”]; if(nil == cell) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:@”myCel”] autorelease]; } cell.text = @”test”; return cell;
}

• -[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0×407ba0
  2009-02-09 03:01:45.159 Test[4285:20b] Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘* -[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0×407ba0’

Now I request you to please help me about what I missed or went wrong in it.
Regards
—danishnajam

Sorry Bill for bothering you. However it ended up being a connection problem in IB. I didn’t have each tab connected to a view controller. I only had them connected to the xib files. Lemme add a word for naive user like me that do connect your Tab Bar in the Main window xib to your custom view Controllers as well.
Cheers
—danishnajam

Hi Danish,

No problem at all, questions that get answered all by themselves are the easiest :)

Let us know when you get an app published!

Hey Bill,

I am trying to get through episode 1 and have encountered the same
problem that Craig originally found…

I followed the tutorial but when I build and run the app in the emulator,
I get the following error.

2009-05-26 15:19:09.354 Recipes[3138:20b] cellForRowAtIndexPath: {0}}
2009-05-26 15:19:09.355 Recipes[3138:20b] * -[UITableViewCell initWithFrame:resuseIndentifier:]: unrecognized selector sent to instance 0×528ff0
2009-05-26 15:19:09.358 Recipes[3138:20b] Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘** -[UITableViewCell initWithFrame:resuseIndentifier:]: unrecognized selector sent to instance 0×528ff0’

I downloaded the example source and confirmed that it matches mine.
Any ideas what the problem might be?

Thanks,
Anthony

Its just a typo in your code,

The method name you are sending is ‘initWithFrame:resuseIndentifier:’ and the proper method name is ‘initWithFrame:reuseIdentifier:’. You should have a warning from the compiler that ‘initWithFrame:reuseIndentifier:’ might not be implemented ( a yellow line in the code).

Hope this helps.

Gah! Yes that was indeed the problem. Sorry to bother you for such a thing,
I will look more closely next time.

No worries, happens to me all the time.

Hi,
I’ve the same problem of Danish with a Tab Bar Application with several xib files loaded in each tab. I’ve added a new tab with a table list and the owner’s file is a my extension of UITableViewController used as delegate and datasource from the table view and with outlet view to the table view. I’ve the following error:
2009-06-03 08:58:53.422 MyApp[628:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIViewController tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x5270f0' 2009-06-03 08:58:53.423 MyApp[628:20b] Stack: (

The solution should be in the message posted by Danish: ”... it ended up being a connection problem in IB. I didn’t have each tab connected to a view controller. I only had them connected to the xib files. Lemme add a word for naive user like me that do connect your Tab Bar in the Main window xib to your custom view Controllers as well …”.
I thought that if in the xib file loaded in the tab the owner’s file is the correct controller for the referenced view all is ok but now seems that I must connect the tab of the MainWindow.xib to the controller, how can I connect them with IB if they are in different xib files? Can you explain me step by step how make it?
Thanks.

Giannandrea

The error message says that an instance of ‘UIViewController’ was sent the message ‘tableView:numberOfRowsInSection:’. That method is part of the table view data source protocol. So my guess is you have a connection from a table view to a ‘File’s Owner’ object that has had its class set to your particular view controller. But the real instance, created in another nib file, has not had its class set.

Check each nib file to make sure all the view controllers have their class set properly.

Good luck.

Hi, just wanted to contribute, I was a little confused. I have the same tab based app that Danish Najam has along with the same error, so I ended up here :)

To make this easier, I will explain my app a little. I have a tab bar, it contains 3 icons (contact, activities & history). I created my application using the xcode template for tab app. Like it suggested I created a separate “MainView” for my contacts so each “entitiy” has it own view.XIB. I then created classes for each controler ie. ContactViewControler.

The part that I was confused on was apparently you have to specify the class (ContactViewControler) in two places
1. on the file’s owner in the ContactView.xib set the class to ContactViewControler, and specify three link
( ContactView.xib)File Owner’s “View” to TableView
TableView’s “Delagate” to File Owner ( ContactView.xib)
TableView’s “Datasource” to File Owner( ContactView.xib)
2. in the MainWindow.xib open Tab Bar Controller, click the contact tab bar button Set its class to ContactViewControler. Also Set its NIB Name to ContactView.xib.

Once I did this all my error went away, luck I had no code issues.

I say all of this to ask, why do we have to specify the controler class twice. more specifically why does the tab bar care, should the NIB file we load take care of all of that and the tab bar is merely a short cut or link to the ContactsView?

Just looking for some clarification, and logical reasoning.
Jeremy

Hi Jeremy,

The ‘File’s Owner’ is not an object, its a proxy. The real object lives in the other nib file. There is where you must set the class. You can leave ‘File’s Owner’s class as NSObject if you want and it would still load. However, the view outlet must be set on a view controller. For the files’ owner to know that it has a view you must set the class to something deeper in the hierarchy than NSObject (namely at least UIViewController). If you want IB to know about your specific outlets then of course you must tell it the file’s owner is of your class.

Another source of info on the files owner is the documentation on the ADC site in the discussion of nib files.

Good luck, and I hope this helps.

Hi Bill,
Guess I’m having a similar problem, but I can’t seem to use the information above to fix it…so here is my problem:

I’m trying to draw various polygon shapes in a UIView.
I have the following method defined in my PolygonShapeView.h:

+ (NSArray )pointsForPolygonInRect:(CGRect)rect numberOfSides:(int)numberOfSides;

When I do, I get the following logged to the debugger console:
.
.
2009-08-28 18:48:34.584 HelloPoly[737:20b] I’ve entered the drawRect method call in PolygonShapeView.m
2009-08-28 18:48:34.584 HelloPoly[737:20b] -[PolygonShapeView pointsForPolygonInRect:numberOfSides:]: unrecognized selector sent to instance 0xd26f30
2009-08-28 18:48:34.585 HelloPoly[737:20b] Terminating app due to uncaught exception ‘NSInvalidArgumentException’, reason: ‘** -[PolygonShapeView pointsForPolygonInRect:numberOfSides:]: unrecognized selector sent to instance 0xd26f30’
2009-08-28 18:48:34.585 HelloPoly[737:20b] Stack: (

and I get my yellow warning in Xcode.

I can’t see that i’ve got typos in the method call. I’ve tried to follow the IB discussions above. My PolygonShapeView view is connected to my controller as a Referencing Outlet, my File’s Owner class is UIApplication with a class outlet to my system defined delegate.

I can’t seem to get a handle on what’s wrong with the selector and why it isn’t recognized. My Xcode warning is that my PolygonShapeView class object may not respond to ‘-pointsForPolygonInRect:numberOfSides:’

Any time and help is much appreciated.

Hi Andrew,

Sorry to be late to respond.

It looks to me like you are sending a class method (the + at the front of the method is what makes it a class method) to an instance.

Instead of [self pointsForPolygonInRect:numberOfSides:] you have to send this message to the class with [[self class] pointsForPolygonInRect:numberOfSides:]. Or you can make that method an instance method (but that seems wrong given the name of the method).

Hope this helps!

Bill,
Thanks very much. That was it. Mixing up the class method definition with an instance receiver. I really appreciate the help. Your explanations are simple for a newbie like me to follow and right on target.

Thanks again!

• Call stack at first throw:
  ( 0 CoreFoundation 0×00f8ebe9 exceptionPreprocess + 185 1 libobjc.A.dylib 0×010e35c2 objc_exception_throw + 47 2 CoreFoundation 0×00f906fb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187 3 CoreFoundation 0×00f00366 forwarding + 966 4 CoreFoundation 0×00efff22 _CF_forwarding_prep_0 + 50 5 Punch 0×00004548 -[ProjectController viewDidLoad] + 184 6 UIKit 0×0036e65e -[UIViewController view] + 179 7 UIKit 0×0036ca57 -[UIViewController contentScrollView] + 42 8 UIKit 0×0037d201 -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 48 9 UIKit 0×0037b831 -[UINavigationController _layoutViewController:] + 43 10 UIKit 0×0037ca86 -[UINavigationController _startTransition:fromViewController:toViewController:] + 326 11 UIKit 0×00377606 -[UINavigationController _startDeferredTransitionIfNeeded] + 266 12 UIKit 0×0037e83e -[UINavigationController pushViewController:transition:forceImmediate:] + 932 13 UIKit 0×003774a0 -[UINavigationController pushViewController:animated:] + 62 14 UIKit 0×00336794 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1140 15 UIKit 0×0032cd50 -[UITableView _userSelectRowAtPendingSelectionIndexPath:] + 219 16 Foundation 0×0003f7f6 __NSFireDelayedPerform + 441 17 CoreFoundation 0×00f6ffe3 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION + 19 18 CoreFoundation 0×00f71594 CFRunLoopDoTimer + 1220 19 CoreFoundation 0×00ecdcc9 __CFRunLoopRun + 1817 20 CoreFoundation 0×00ecd240 CFRunLoopRunSpecific + 208 21 CoreFoundation 0×00ecd161 CFRunLoopRunInMode + 97 22 GraphicsServices 0×018c3268 GSEventRunModal + 217 23 GraphicsServices 0×018c332d GSEventRun + 115 24 UIKit 0×002cf42e UIApplicationMain + 1160 25 Punch 0×00002896 main + 84 26 Punch 0×00002839 start + 53
  )
  terminate called after throwing an instance of ‘NSException’

/>2011-02-06 22:18:26.297 Punch[34634:207] Selected punch object: Projects
2011-02-06 22:18:26.301 Punch[34634:207] : unrecognized selector sent to instance 0x4d13470
2011-02-06 22:18:26.304 Punch[34634:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '[NSPlaceholderArray arrayWithObjects:]: unrecognized selector sent to instance 0x4d13470'

My method is here in RootViewController:

- (void)tableView:(UITableView *)aTableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { // select static row and view controller Punch *obj = [self.punchList punchAtIndex:indexPath.row]; NSLog("Selected punch object: %”, obj.name);

if (0 == indexPath.row) {
       self.projectController.key = @"project";
       self.projectController.title = @"Projects";
   }

/>}

My design is as follows:

I started with an iPad split-view template and then I replaced the RootViewController popOver with a UINavigationController. I also created a separate RootViewController.xib file with a TableView. I select “Projects” and then bomb with the above error. I was loading the RootViewController’s view with Objects.name in the cells. I simplified this table with strings in an NSArray. I thought that the Punch object in the View (e.g. punch.name) was really not a String. The NSLog works and I see the String selected.

I’m really stumped.

Thanks for any help folks.

I solved my problem partially. I solved the problem where I select from the RootViewController view and now my SecondLevelController is placed on the stack and instantiated. The problem is that I used data from the iPhone SDK book where “key” is used for DVDCabinetController. I want to use this setup so that I can pull from the database a list of “Projects”,”Applications”, and “Products” from the root view.

I commented out all the array and dictionary stuff and the selector issue went away. It was because “key” is not recognized or set I don’t think. Not sure:

- (void)tableView:(UITableView *)aTableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    // select static row and view controller
    //Punch *obj = [self.punchList punchAtIndex:indexPath.row];
    //NSLog(@"Selected punch object: %@", obj.name);

    if (0 == indexPath.row) {

        [self.projectController setKey:@"project"];
        self.projectController.title = @"Projects";
    }

    projectController = [[ProjectController alloc] initWithNibName:@"ProjectController" bundle:nil];
    [self.navigationController pushViewController:projectController animated:YES];
    [projectController release];    

}

And the projectController code:

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
 - (void)viewDidLoad {
     arrayData = [[NSArray alloc] initWithObjects:@"Project-1",@"Project-2",@"Project-3",@"Project-4",@"Project-5",nil];
     [super viewDidLoad];
     self.title = @"Project";

     // keys
     //NSArray *keys = [NSArray arrayWithObjects:@"project",@"application",@"product",nil];

     // arrays for each selection
     //NSArray *projectOBJs = [NSArray arrayWithObjects:@"Project-DLW1",@"Project-DLW2",nil];
     //NSArray *applicationOBJs = [NSArray arrayWithObjects:@"Application-DLW10",@"Application-DLW20",nil];
     //NSArray *productOBJs = [NSArray arrayWithObjects:@"Product-DLW100",@"Product-DLW200",nil];

     // array of arrays
     //NSArray *values = [NSArray arrayWithObjects:projectOBJs, applicationOBJs, productOBJs, nil];

     // data holds keys and values
     //data = [[NSDictionary alloc] initWithObjects:values forKeys:keys];

 }

The fixed array works but use of “key” gives the selector error. I haven’t brought in the data model yet so that’s why I’m just looking for good design. I like the concept of calling the projectController maybe SecondaryViewController and switching on “key” or similar.

Can anyone explain why I get a selector error?

Thanks in advance,

David