任何人都可以给出目标 C 中针对普通类而不是类别或协议的前向声明的示例吗？

Question

任何人都可以给出目标 C 中针对普通类而不是类别或协议的前向声明的示例吗？

Answer 1

/*
  using a forward declaration of NSDocument, there's no need
  for every source that encounters this header to include AppKit,
  allowing much faster compile times and reducing dependency
  changes for clients.

  of course, MONThang.m will need to include AppKit to use NSDocument
  - but the clients using MONThang do not need to import AppKit.
*/

@class NSDocument; // << the forward declaration

@interface MONThang : NSObject
{
    NSDocument * document;
}

@end