1 @interface A : NSObject
 2 
 3 @end
 4 @implementation A
 5 
 6 @end
 7 ////
 8 @interface AA : A
 9 
10 @end
11 @implementation AA
12 
13 @end
14 ////
15 @interface B : NSObject
16 
17 @end
18 @implementation B
19 
20 @end
21 int main(int argc, char * argv[]) {
22     A *a = [[A alloc]init ];
23     // 运行结果1
24     NSLog(@"%d",[a isKindOfClass:[NSObject class]]);
25     
26     @autoreleasepool {
27         return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
28     }
29 }