objective-c - 为委派导入视图控制器不起作用

Question

我有一个视图控制器 FirstViewController，它有一个子类 FourthViewController。FirstViewController 的接口是：

#import "FourthViewController.h"
@interface FirstViewController : UIViewController <FourthViewControllerDelegate>

在 FourthViewController 的 .h 中，我有：

#import "FirstViewController.h"

@protocol FourthViewControllerDelegate
-(void) updateLabel;
@end

@interface FourthViewController : FirstViewController 

@property (weak, nonatomic) id<FourthViewControllerDelegate>delegate;

这给了我错误消息：找不到'FirstViewController'的接口声明，'FourthViewController'的超类我不确定为什么会发生这个错误。任何建议都会有所帮助。

Answer 1

将委托.h与控制器保存在同一个文件中对您来说真的很重要吗？我把它放到一个单独的.h文件中，整个过程对我有用。像这样：

//FirstViewController.h
#import <Foundation/Foundation.h>

#import "FourthViewControllerDelegate.h"
@interface FirstViewController : UIViewController <FourthViewControllerDelegate>
@end

//FourthViewControllerDelegate.h
#import <Foundation/Foundation.h>

@protocol FourthViewControllerDelegate <NSObject>
-(void) updateLabel;
@end

//FourthViewController.h
#import <Foundation/Foundation.h>

#import "FirstViewController.h"
#import "FourthViewControllerDelegate.h"

@interface FourthViewController : FirstViewController

@property (weak, nonatomic) id<FourthViewControllerDelegate>delegate;
@end