isMemberOfClass：对象是否是某类型对象。isKindOfClass：对象时否是某类型或类型子类的对象。isSubclassOfClass、isAncestorOfObject：类对象是否是另一个类型的子类、父类。respondsToSelector：是否能响应某方法。conformsToProtocol：是否遵循某协议。
class与object_getClass：
- 实例
class = object_getClass(self)
- 类
class返回自身；object_getClass(类对象)返回元类。
实现：
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| // 判断当前对象、类的isa指向是不是类、原类
+ (BOOL)isMemberOfClass:(Class)cls {
return object_getClass((id)self) == cls;
}
- (BOOL)isMemberOfClass:(Class)cls {
return [self class] == cls;
}
// 判断当前对象、类的isa是不是类、元类或者其子类类型
+ (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = object_getClass((id)self); tcls; tcls = tcls->superclass) {
if (tcls == cls) return YES;
}
return NO;
}
- (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = [self class]; tcls; tcls = tcls->superclass) {
if (tcls == cls) return YES;
}
return NO;
}
Class object_getClass(id obj)
{
if (obj) return obj->getIsa();
else return Nil;
}
|
显然isKindOfClass范围更大，当调用对象和参数都是类时，类对象的isa指向元类对象，而其元类的superclass指向class对象，所以满足条件返回YES。所以[instance/class isKindOfClass:[NSObject class]];都返回 1。
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| @interface Person : NSObject
@end
......
BOOL res1 = [[NSObject class] isKindOfClass:[NSObject class]];
BOOL res2 = [[NSObject class] isMemberOfClass:[NSObject class]];
BOOL res3 = [[Person class] isKindOfClass:[Person class]];
BOOL res4 = [[Person class] isMemberOfClass:[Person class]];
NSLog(@"%d,%d,%d,%d", res1, res2, res3, res4);
......
// 1,0,0,0
|