How to get rid of the 'undeclared selector' warning

Question

I want to use a selector on an NSObject instance without the need for an implemented protocol. For example, there\'s a category method that should set an error prop

Answer 1

I was able to get the warning to go away by adding thenothing method (disclosure: I didn't think of this but found it by googling on scheduledtimerwithtimeinterval)

    [NSTimer scheduledTimerWithTimeInterval:[[NSDate distantFuture] timeIntervalSinceNow]
                                     target:self
                                   selector:@selector(donothingatall:)
                                   userInfo:nil
                                    repeats:YES];


    [[NSRunLoop currentRunLoop] run];

    HTTPLogVerbose(@"%@: BonjourThread: Aborted", THIS_FILE);

    }
}

+ (void) donothingatall:(NSTimer *)timer
{

}

While I appreciate knowing how to hide the warning, fixing it is better and neither Sergio's nor Relkin's techniques worked for me, for unknown reasons.

Answer 2

You can turn it off in Xcode like in the screenshot:

Answer 3

You can also cast the object in question to an id first to avoid the warning:

if ([object respondsToSelector:@selector(myMethod)]) {
    [(id)object myMethod];
}

Answer 4

Another way to avoid this warning is to make sure your selector method looks like this:

-(void) myMethod :(id) sender{
}

Don't forget "(id) sender" if you want to accept any sender or specify a type of a sender object if you prefer.

Answer 5

Have a look at NSSelectorFromString.

 SEL selector = NSSelectorFromString(@"setError:");
 if ([self respondsToSelector:selector])

It will allow you to create a selector at runtime, instead of at compile time through the @selector keyword, and the compiler will have no chance to complain.

Answer 6

If your class implements the setError: method (even by declaring dynamic the setter of the eventual error property) you might want to declare it in your interface file ( .h), or if you don't like to show it that way you could try with the PrivateMethods tricky trick:

@interface Yourclass (PrivateMethods)

- (void) yourMethod1;
- (void) yourMethod2;

@end

just before your @implementation , this should hide the warnings ;).