respondsToTest.m

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
	
	NSArray *tests = [NSArray arrayWithObjects: [NSMutableDictionary dictionary], [NSDictionary dictionary], nil];	
	
	SEL sel = @selector(setObject:forKey:);
	
	for(id obj in tests) {
		BOOL result = [obj respondsToSelector:sel];
		NSLog(@"%@ respondsToSelector: %@ => %@", 
			  NSStringFromClass([obj class]),
			  NSStringFromSelector(sel), 
			  (result ? @"YES" : @"NO"));		
	}
	
	
	[pool drain];
    return 0;
}