選擇器是發(fā)送消息的機制决瞳，通過 @selector（方法名）或者 創(chuàng)建SEL 類型的變量來調(diào)用執(zhí)行方法淑翼。

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//通過方法名創(chuàng)建選擇器
        SEL sel=@selector(dogEat);
        
        Dog *xiaobai = [[Dog alloc]init];
        
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"  //告訴編譯器不會造成內(nèi)存泄漏
        if ([xiaobai respondsToSelector:sel]){ //判斷對象所屬類是否實現(xiàn)了selector中的方法
            NSLog(@"方法1");
        [xiaobai performSelector:sel]; //通過performSelector關鍵字亚脆，執(zhí)行了選擇器中的方法乱陡。
        }
    
        
        
//用方法名對的字符串對象生成選擇器
        SEL sel2=NSSelectorFromString(@"dogBark:");
        
         if ([xiaobai respondsToSelector:sel2]){
             NSLog(@"方法2");
             [xiaobai performSelector:sel2 withObject:[NSNumber numberWithInt:5]];
        }

//用方法名的c語言字符串生成選擇器
        SEL sel3 = sel_getUid("dogBark:");
        if ([xiaobai respondsToSelector:sel3]) {
            NSLog(@"方法3");
            [xiaobai dogBark:[NSNumber numberWithInt:4]];
        }
        
//獲取選擇器中的方法名
        NSLog(@"name = %@", NSStringFromSelector(sel)); //方法名字符串對象
        NSLog(@"name = %s", sel_getName(sel2));