espondsToSelector判断是否实现了某方法

Tester.h

#import <Foundation/Foundation.h>


@interface Tester : NSObject {

}

-(void) test:(NSString*) msg;

-(void) notImp;

@end

Tester.m

#import "Tester.h"

@implementation Tester

-(void) test:(NSString*) msg
{
 NSLog(@"%@", msg);
}

@end

注意：没有实现notImp方法

main.m

#import <Foundation/Foundation.h>
#import "Tester.h"

int main (int argc, const char * argv[])
{

 NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

 id tester = [[Tester alloc] init];//注意，这里使用id
 
 SEL testSelector = @selector(test:);
 SEL notImpSelector = @selector(notImp:);

if([tester respondsToSelector:testSelector])
 {
//tester.m中实现了test方法
 [tester test:@"invoke test method"];
 }
if([tester respondsToSelector:notImpSelector])
 {
//test.m中没有实现此主就去
 [tester notImp];
 }


 [pool drain];
return 0;
}