为什么要使用嵌套类？(Why would one use nested classes?)

 已经做了5年的Objective-c，所以请耐心等待。 
 
 我很难找到清楚解释为什么你想要在另一个内部嵌套类定义的文档。 
 
 如果我有两个类，如下所示，对我来说，它们是在彼此之上和之下声明的。 您甚至可能希望拥有引用另一个的嵌套属性。 
 
class DataImporter {
     }

class DataGenerator {
     }
 
 但我不明白为什么像下面这样的嵌套安排会有用。 
 
class DataImporter {
     class DataGenerator {
     } }

Been doing objective-c for 5 years, so please bear with me.
 
I'm struggling to find documentation that clearly explains why you would want to nest a class definition, inside of another.
 
If I had two classes like the following, it makes sense to me that they are declared above and below each other. You may even want to have a nested property that references the other.
 
class DataImporter {
     }

class DataGenerator {
     }
 
But I don't understand why a nested arrangement like the following would be useful.
 
class DataImporter {
     class DataGenerator {
     } }

原文：https://stackoverflow.com/questions/35947901