isMemberOfClass的用法；返回假

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问题描述

在下面的代码中，我认为第二个条件为true，但事实证明它为false.我想念什么吗?请帮助我理解.

In the code below I thought the second condition would be true, but it is turning out as false. Am I missing something? Please help me understand.

NSArray *array = [[NSArray alloc] init];
NSLog(@"%@", NSStringFromClass([array class]));

if ([array isMemberOfClass:[NSObject class]]) {

    NSLog(@"Member NSObject"); //Didn't print; 
}

if ([array isMemberOfClass:[NSArray class]]) {

    NSLog(@"Member NSArray"); //Didn't print; I don't understand why?
}

if ([array isKindOfClass:[NSObject class]]) {

    NSLog(@"Kind of NSObject"); //Printed; Expected
}

if ([array isKindOfClass:[NSArray class]]) {

    NSLog(@"Kind of NSArray"); //Printed; Expected
}

修改

我将NSArray的子类创建为MyArray，并使用isMemberOfClass如下测试其实例

I created sub class of NSArray as MyArray and tested its instance using isMemberOfClass as below

if ([myArray isMemberOfClass:[MyArray class]]) {

    NSLog(@"Member MyArray"); //Printed;
}

所以，我猜想isMemberOfClass在NSArray上是不可能的，可能在其他一些框架类上也是如此.

So, I guess isMemberOfClass not possible on NSArray, probably on some other framework classes as well.

谢谢.

推荐答案

这是正确的行为.尝试检查该对象的实际类:

This is the correct behavior. Try inspecting the actual class for that object:

NSArray *array = [[NSArray alloc] init];
NSLog(@"%@", NSStringFromClass([array class]));

您得到的输出类似于:

2013-02-15 23:42:31.272 Project[91998:c07] __NSArrayI

因此，实际的类是__NSArrayI(NSArray的私有子类)，而不是NSArray本身.通常，isKindOfClass:会提供更有用的结果.

So the actual class is __NSArrayI (a private subclass of NSArray), not NSArray itself. Typically, isKindOfClass: provides more useful results.

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