OC基础 - isMemberOfClass | isKindOfClass

isMemberOfClass | isKindOfClass

1 - 猜想以下代码输出的结果

 1 #import <Foundation/Foundation.h>
 2 #import <objc/runtime.h>
 3 @interface Person : NSObject
 4
 5 @end
 6 @implementation Person
 7
 8 @end
 9
10 int main(int argc, const char * argv[]) {
11     @autoreleasepool {
12
13         NSLog(@"%d", [[NSObject class] isKindOfClass:[NSObject class]]);
14         NSLog(@"%d", [[NSObject class] isMemberOfClass:[NSObject class]]);
15         NSLog(@"%d", [[Person class] isKindOfClass:[Person class]]);
16         NSLog(@"%d", [[Person class] isMemberOfClass:[Person class]]);
17
18         NSLog(@"========== 以上代码等价如下 =========");
19
20         NSLog(@"%d", [NSObject isKindOfClass:[NSObject class]]);
21         NSLog(@"%d", [NSObject isMemberOfClass:[NSObject class]]);
22         NSLog(@"%d", [Person isKindOfClass:[Person class]]);
23         NSLog(@"%d", [Person isMemberOfClass:[Person class]]);
24
25     }
26     return 0;
27 }

日志信息

2 - isMemberOfClass 和 isKindOfClass 源代码

 1 - (BOOL)isMemberOfClass:(Class)cls {
 2     return [self class] == cls;
 3 }
 4 - (BOOL)isKindOfClass:(Class)cls {
 5     for (Class tcls = [self class]; tcls; tcls = tcls->superclass) {
 6         if (tcls == cls) return YES;
 7     }
 8     return NO;
 9 }
10
11
12 + (BOOL)isMemberOfClass:(Class)cls {
13     return object_getClass((id)self) == cls;
14 }
15
16
17 + (BOOL)isKindOfClass:(Class)cls {
18     for (Class tcls = object_getClass((id)self); tcls; tcls = tcls->superclass) {
19         if (tcls == cls) return YES;
20     }
21     return NO;
22 }

结论：isMemberOfClass  左边对象（类对象）是否等于右边所传进的类对象，是相等的关系

isKindOfClass 左边对象（类对象）是否等于右边所传进的类对象或是其子对象，是相等或是其子对象的关系

3 - 代码实例

 1 #import <Foundation/Foundation.h>
 2 #import <objc/runtime.h>
 3 @interface Person : NSObject
 4
 5 @end
 6 @implementation Person
 7
 8 @end
 9
10 int main(int argc, const char * argv[]) {
11     @autoreleasepool {
12
13         // ----------------------------类方法
14         NSLog(@"%d", [Person isMemberOfClass:object_getClass([Person class])]); // 1
15
16         // NSObject
17         NSLog(@"%d", [Person isKindOfClass:object_getClass([NSObject class])]); // 1
18         NSLog(@"%d", [Person isKindOfClass:[NSObject class]]);// 1
19
20         // ----------------------------实例方法
21         id person = [[Person alloc] init];
22
23         NSLog(@"%d", [person isMemberOfClass:[Person class]]);   // 1
24         NSLog(@"%d", [person isMemberOfClass:[NSObject class]]); // 0
25         NSLog(@"%d", [person isKindOfClass:[Person class]]);     // 1
26         NSLog(@"%d", [person isKindOfClass:[NSObject class]]);   // 1
27
28     }
29     return 0;
30 }