isKindOfClass的實現程式碼如下：
-(BOOL)isKindOfClass:(Class)aClass
{
for (Class tcls = isa; tcls; tcls-> superclass) {
if (tcls == aClass) {
return YES;
}
}
return NO;
}
isMemberOfClass的實現程式碼如下：
-(BOOL)isMemberOfClass:(Class)aClass
{
return isa == aClass;
}
如果呼叫這兩個方法的是物件，isa指標指向的是物件的Class，如果呼叫這兩個方法的是Class，isa指標指向的是類的元類，接下來通過一張圖介紹一下物件，類，元類之間的關係：
如圖：Father為繼承自NSObject的類，Son為繼承自Father的類，接下來，我們們通過幾個例項來驗證上述方法的正確性：
Son *sonObject = [Son new];
Father *fatherObject = [Father new];
BOOL ret1 = [Son isKindOfClass:[fatherObject class]];//0
BOOL ret2 = [sonObject isKindOfClass:[Father class]];//1
BOOL ret3 = [Son isMemberOfClass:[fatherObject class]];//0
BOOL ret4 = [sonObject isMemberOfClass:[Father class]];//0
NSLog(@"%d------%d-------%d-------%d",ret1,ret2,ret3,ret4);
列印結果：
分析這四個問題答案的過程如下：
/*
Son->(isa)MetaClassOfSon->(superClass)MetaClassOfFather->(superClass)MetaClassOfNSObjetc->(superClass)NSObject->(superClass)nil
[father class] = Father
*/
BOOL ret1 = [Son isKindOfClass:[fatherObject class]];//0
/*
sonObject->(isa)Son->(superClass)Father->(superClass)NSObject->(superClass)nil
[Father class] = Father
*/
BOOL ret2 = [sonObject isKindOfClass:[Father class]];//1
/*
Son->(isa)MetaClassOfSon
[fatherObject class] = Father
*/
BOOL ret3 = [Son isMemberOfClass:[fatherObject class]];//0
/*
sonObject->(isa)Son
[Father class] = Father
*/
BOOL ret4 = [sonObject isMemberOfClass:[Father class]];//0