iOS isKindOfClass & isMemberOfClass

原始链接
原文链接
官方文档
官方文档
Demo-Github

isKindOfClass

Returns a Boolean value that indicates whether the receiver is an instance of given class or an instance of any class that inherits from that class.
返回一个布尔值，该值指示接收方是给定类的实例还是从该类继承的任何类的实例。

• 1. 对象方法
• 2. 参数为Class
• 3. 改对象是否是该类的，或者该类父类的一个实例对象

• isMemberOfClass
  Returns a Boolean value that indicates whether the receiver is an instance of a given class.
  返回一个布尔值，该值指示接收方是否是给定类的实例

• 1. 对象方法
• 2. 参数为Class
• 3. 改对象是否是该类的一个实例对象

BOOL res1 = [(id)[NSObject class] isKindOfClass:[NSObject class]];
BOOL res2 = [(id)[NSObject class] isMemberOfClass:[NSObject class]];
BOOL res3 = [(id)[Person class] isKindOfClass:[Person class]];
BOOL res4 = [(id)[Person class] isMemberOfClass:[Person class]];

+ (Class)class OBJC_SWIFT_UNAVAILABLE("use 'aClass.self' instead");
+ (Class)class {
    return self;
}
+ (BOOL)isKindOfClass:(Class)cls {
    for (Class tcls = object_getClass((id)self); tcls; tcls = tcls->superclass) {
        if (tcls == cls) return YES;
    }
    return NO;
}
Class object_getClass(id obj)
{
    if (obj) return obj->getIsa();
    else return Nil;
}
+ (BOOL)isMemberOfClass:(Class)cls {
    return object_getClass((id)self) == cls;
}

• 1. [NSObject class] 返回值是？
     • 返回NSObject这个类,有一个坑在这里就是NSObject的metaclass 是指向自己的，
     • 因为这是最顶层。
     • 所以 res1 YES， NSObject 是自己父类的子类的isa
• 2. NSObject 是自己父类的instance, 但是不是当前类的instance
• 3 和 4 同理
  res1:1
  res2:0
  res3:0
  res4:0

续集

BOOL res5 = [(id)[Person new] isMemberOfClass:[Person class]];
BOOL res6 = [(id)[Person new] isKindOfClass:[Person class]];
BOOL res7 = [(id)[Teacher new] isMemberOfClass:[Person class]];
BOOL res8 = [(id)[Teacher new] isKindOfClass:[Person class]];

 res5:1 
 res6:1 
 res7:0 
 res8:1