objective-c - 任何人都可以举例说明在 Objective-C 中针对普通类而不是类别或协议(protocol)的前向声明吗？

Question

谁能给出在 Objective-C 中针对普通类而不是类别或协议(protocol)的前向声明的示例？

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