cannot find protocol declaration for "RefreshAudioListViewDelegate"

1.PlayerListViewController.h文件时，首先发现#import "PlayerController.h",编译器会跑到PlayerController.h中。

2.在PlayerController.h中首先发现#import "PlayerListViewController.h"，编译器又会到PlayerListViewController中加载内容。

@interface PlayerListViewController : UIViewController< RefreshAudioListViewDelegate>这一句的时候，由于在PlayerController中定义代理的语句还没有加载，所以编译器会报错：

cannot find protocol declaration for "RefreshAudioListViewDelegate"

#import "PlayerListViewController.h"