无法从呈现视图控制器

Question

委托报关

// 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 

代表从didSelectRowAtIndexPath方法称为访问委托方法：

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

的VC应接收该消息

#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 

介绍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]; 
} 

委托方法实现

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

我已经经历了多线程上读到这里，还没有任何运气。起初，我在展示FolderListVC（即vc.delegate = self）时没有引用ProjectListVC设置。虽然这似乎不是问题。我正在研究为iPad构建的应用程序，并将其扩展到所有设备上。这里的实现工作（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创建问题，因为它没有设置FolderListViewController委托。你可以尝试这样。

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

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