Question

委托声明

// FolderListViewController.h
#import <UIKit/UIKit.h>
#import "Folder.h"

@protocol FolderSelectionDelegate <NSObject>

@required
- (void)setFolder:(Folder *)folder;

@end

@interface FolderListViewController : UITableViewController

@property (nonatomic, assign) id<FolderSelectionDelegate> delegate;

- (IBAction)showDashboard:(id)sender;

@end

从didSelectRowAtIndexPath：

调用Delegate

// FolderListViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    [self.delegate setFolder:dataSource[indexPath.row]];
}

应该接收消息的VC

#import <UIKit/UIKit.h>
#import "FolderListViewController.h"
#import "Folder.h"

@interface ProjectListViewController : UITableViewController <FolderSelectionDelegate, UISplitViewControllerDelegate, UISearchBarDelegate, UINavigationControllerDelegate>

@property (nonatomic,retain)UIActivityIndicatorView *activityIndicatorObject;
@property (nonatomic, copy)Folder *folder;


-(void)loadProjects:(Folder*)folder;

@end

呈现VC的行动

- (void)foldersButtonTapped {
    UINavigationController *vc = [[UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle:nil] instantiateViewControllerWithIdentifier:@"FolderListNavController"];
    vc.delegate = self;
    [self presentViewController:vc animated:YES completion:nil];
}

委托方法实施

- (void)setFolder:(Folder *)folder {
    _folder = folder;
    [self loadProjects:folder];
}

我在这里阅读了多个主题并且没有运气。首先，在呈现FolderListVC（即vc.delegate = self）时，我没有引用ProjectListVC设置。尽管如此，这似乎不是问题所在。我正在开发一款专为iPad打造的应用程序，并将其扩展为适用于所有设备。这里的实现是有效的（它被设置为分割视图控制器）。任何帮助将不胜感激

Answer 1

我认为UINavigationcontroller正在创建问题，因为它没有设置FolderListViewController委托。你能尝试这样吗。

 FolderListViewController *vc=[self.storyboard instantiateViewControllerWithIdentifier:@"FolderListViewController"];

    vc.delegate=self; // protocol listener
    [self.navigationController pushViewController:vc animated:YES];

无法从显示的视图控制器访问委托方法

1 个答案: