Determine if a subclass implements a specific selector.

ImplementsSelectorSample.m

if ([MyView implementsSelector:@selector(someMethod:)])
    NSLog(@"Implemented");

NSObject+SPXAdditions.h

#import <Foundation/Foundation.h>

@interface NSObject (SPXAdditions)

+ (BOOL)implementsSelector:(SEL)selector;

@end

NSObject+SPXAdditions.m

#import "NSObject+SPXAdditions.h"
#import <objc/runtime.h>

@implementation NSObject (SPXAdditions)

+ (BOOL)implementsSelector:(SEL)selector
{
    int unsigned numMethods;

    const char *className = [NSStringFromClass([self class]) UTF8String];
    Method *methods = class_copyMethodList(objc_getClass(className), &numMethods);

    for (int i = 0; i < numMethods; i++)
    {
        if (selector == method_getName(methods[i]))
            return YES;
    }

    return NO;
}

@end