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

While the correct answer likely lies in informing Xcode through imports or registering the selector that such a selector exists, in my case I was missing a semi-colon. Make sure before you "fix" the error that perhaps, the error is correct and your code isn't. I found the error in Apple's MVCNetworking sample, for instance.

Answer 2

Another option would be to disable the warning with:

#pragma GCC diagnostic ignored "-Wundeclared-selector"

You can place this line in the .m file where the warning occurs.

Update:

It works also with LLVM like this:

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wundeclared-selector"

... your code here ...

#pragma clang diagnostic pop

Answer 3

I got that message to go away by #include'ing the file with the method. Nothing else was used from that file.

Answer 4

A really comfortable macro to put in your .pch or Common.h or wherever you want:

#define SUPPRESS_UNDECLARED_SELECTOR_LEAK_WARNING(code)                        \
_Pragma("clang diagnostic push")                                        \
_Pragma("clang diagnostic ignored \"-Wundeclared-selector"\"")     \
code;                                                                   \
_Pragma("clang diagnostic pop")                                         \

It's an edit of this question for similar issue...

Answer 5

I think this is because for some odd reason the selector isn't registered with the runtime.

Try registering the selector via sel_registerName():

SEL setErrorSelector = sel_registerName("setError:");

if([self respondsToSelector:setErrorSelector]) {
   [self performSelector:setErrorSelector withObject:[NSError errorWithDomain:@"SomeDomain" code:1 userInfo:nil]];
}

Answer 6

I realise I'm a bit late to this thread but for completeness, you can globally turn off this warning using the target build settings.

In section, 'Apple LLVM warnings - Objective-C', change:

Undeclared Selector - NO