Objective-C 'Robot' may not respond to '-nothingToDo'

Question

Guys, I have two classes AppController and Robot.

AppController.h
#import <Cocoa/Cocoa.h>
#import "Robot.h"

@interface AppController : NSObject {

 Robot *myRobot;

}
- (IBAction)initPort:(id)sender;


AppController.m

#import "AppController.h"
@implementation AppController


- (IBAction)initPort:(id)sender
{
 [myRobot nothingDo];
}
@end

Robot.h

#import <Cocoa/Cocoa.h>
@interface Robot : NSObject {

}
-(void)nothingToDo:(id)sender;


Robot.m
#import "Robot.h"

@implementation Robot

-(void)nothingToDo:(id)sender
{
    NSLog(@"bla-bla-bla");
}

When I'm trying to run I see 'Robot' may not respond to '-nothingToDo' and -(void)nothingToDo is not being performed. What 's wrong?

Answer 1

The colons in an Objective-C method is significant. Try

[myRobot nothingToDo:sender];

instead.

Answer 2

When compiling AppController.m the compiler is not aware of private -nothingToDo method since it does not appear in Robot.h. This is why a warning is issued.

Actually, this method doesn't exist, only -nothingToDo: (note the : meaning an argument is needed). This is why the method is not called.

Answer 3

Start by making sure myRobot references a valid Robot object.

Answer 4

You're sending the message nothingDo, and not nothingToDo (might be just a typo).

Furthermore, you forgot the sender parameter.

Try this:

- (IBAction)initPort:(id)sender
{
   [myRobot nothingToDo:sender];
}

This should work, provided myRobot is a properly allocated and initializedRobot object.