尝试将 _NSFaultingMutableSet 识别为 NSSet 的成员
我试图将对托管对象的通用查询的结果识别为 NSSet。当前返回的类是 _NSFaultingMutableSet 的成员，这显然是相关的，但 isMemberOf:[NSSet class] 和 isKindOf:[NSSet class] 调用失败。
鉴于 Cocoa 没有直接实现 NSSet，所以管道中有一些空气并不奇怪，但我想知道我是否搞乱了一些明显的东西，或者这需要更高级别的功夫比我拥有的。
代码如下：
SEL selector = NSSelectorFromString(someString);
if(![self respondsToSelector:selector]){
NSLog(@"Error processing item");
return;
}
id items = [self performSelector:selector];
Class itemsClass = [items class];
if ( [itemsClass isKindOfClass:[NSSet class]]) {
// do something
}
I'm trying to recognize the result of a generic query to a managed object as an NSSet. Currently the class returned is a member of _NSFaultingMutableSet, which is clearly related, but fails the isMemberOf:[NSSet class] and isKindOf:[NSSet class] calls.
Given that Cocoa doesn't do a direct implementation of NSSet, it's not surprising that I've got some air in the pipes, but I'm wondering if I'm messing something obvious up or this requires a higher grade of kung-fu than I possess.
Code follows:
SEL selector = NSSelectorFromString(someString);
if(![self respondsToSelector:selector]){
NSLog(@"Error processing item");
return;
}
id items = [self performSelector:selector];
Class itemsClass = [items class];
if ( [itemsClass isKindOfClass:[NSSet class]]) {
// do something
}
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哈!像往常一样，RTFM 解决了我的问题。事实证明，如果您不应该像我一样在类本身上调用 isKindOf: ，而是在特定实例上调用 isKindOf: 。啧啧。
Ha! My problem was solved, as usual, by RTFM. It turns out that if you are NOT supposed to call isKindOf: on a class itself, as I was, but rather on the particular instance. Tsk tsk.
或者， NSObject 确实有
isSubclassOfClass:类方法（在 Mac OS X 10.2 中引入）。您可以这样做：尽管如此，简单地测试实例本身可能更容易。
Alternatively, NSObject does have an
isSubclassOfClass:class method (introduced in Mac OS X 10.2). You could do:Although, it probably is easier to simply test the instance itself.