@interface A : NSObject

 @end

 @implementation A

 @end

 ////

 @interface AA : A

 @end

 @implementation AA

 @end

 ////

 @interface B : NSObject

 @end

 @implementation B

 @end

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

     A *a = [[A alloc]init ];

     // 运行结果1

     NSLog(@"%d",[a isKindOfClass:[NSObject class]]);

     @autoreleasepool {

         return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));

     }

 }