respondsToSelector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;
}