Question

我试图实现两个委托方法。我认为我已正确编写协议，并且我正确地分配了委托，因为我在另一个工作正常的委托/协议上仔细建模。但是，代表方法在被调用时不会触发，或者至少看起来像是在发生什么。我已经在调用委托方法的地方设置了断点，也在方法本身设置了断点，但似乎控件永远不会到达它们。

以下是我认为的相关代码。来自notifyingVC.h文件：

//  AddCategoryVC.h
//  YYYYYY
//
//  Created by XXXXXX on 2/19/15.
//  Copyright (c) 2015 XXXXXX. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "WMMGCategory.h"
//#import "AddTransactionVC.h"

@class AddTransactionVC;

@protocol AddCategoryDelegate <NSObject>

-(void) addCategoryDidSave : (WMMGCategory *) brandNewCategory;

-(void) addCategoryDidCancel : (WMMGCategory *) categoryToDelete;

@end

@interface AddCategoryVC : UIViewController

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

来自notifyingVC.m文件：

//  AddCategoryVC.m
//  YYYYYY
//
//  Created by XXXXXX on 2/19/15.
//  Copyright (c) 2015 XXXXXX. All rights reserved.
//

#import "AddCategoryVC.h"
#import "WMMGCategory.h"

@interface AddCategoryVC ()


@end


@implementation AddCategoryVC

…Blah de blah…

- (IBAction)saveCategory:(UIBarButtonItem *)sender
{
    if (self.nooCatTextField.text.length < 1)
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"New category not identified"
                                                        message:@"Please enter a name for the new category or cancel"
                                                       delegate:nil
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil];
        [alert show];
    }

    else
    {
        self.brandNewCategory.name = [self.nooCatTextField.text uppercaseString];
        [self.delegate addCategoryDidSave:self.brandNewCategory];
    }

}

- (IBAction)cancelCategory:(UIBarButtonItem *)sender
{
    [self.delegate addCategoryDidCancel:self.brandNewCategory];
}

来自DelegateVC.h文件：

//
//  AddTransactionVC.h
//  YYYYYY
//
//  Created by XXXXXX on 2/6/15.
//  Copyright (c) 2015 XXXXXX. All rights reserved.
//

#import <UIKit/UIKit.h>
#import <MagicalRecord/CoreData+MagicalRecord.h>

#import "WMMGTransaction.h"
#import "AddCategoryVC.h"
#import "WMMGCategory.h"

来自DelegateVC.m标题：

//
//  AddTransactionVC.m
//  YYYYYY
//
//  Created by XXXXXXXX on 2/6/15.
//  Copyright (c) 2015 XXXXXX. All rights reserved.
//

#import "AddTransactionVC.h"

@interface AddTransactionVC ()

@end

@implementation AddTransactionVC

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    AddCategoryVC *acvc = [[AddCategoryVC alloc]init];

    acvc.delegate = self;
}

最后，从DelegateVC.m文件中，委托方法本身：

#pragma mark - New category delegate methods

-(void)addCategoryDidSave:(WMMGCategory *)brandNewCategory
{
    NSManagedObjectContext *localContext = [NSManagedObjectContext MR_contextForCurrentThread];
    [localContext MR_saveToPersistentStoreAndWait];
    [self.navigationController dismissViewControllerAnimated:YES completion:nil];
}

-(void)addCategoryDidCancel:(WMMGCategory *)categoryToDelete
{
    [categoryToDelete MR_deleteEntity];
    [self.navigationController dismissViewControllerAnimated:YES completion:nil];

}

我在前面承认我可能会做出一些愚蠢的错字或其他什么，但我确实感谢有人看看我做错了什么。

编辑，根据@ rdelmar的答案如下：

这是AddCategoryVC实例的创建代码：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSString *identifier = segue.identifier;

    if ([identifier isEqualToString:@"CatSelectSegue"])
    {
        UIViewController *dvc = segue.destinationViewController;
        UIPopoverPresentationController *catSelPPC = dvc.popoverPresentationController;
        if (catSelPPC)
        {
            catSelPPC.delegate = self;
        }
    }

    else if ([identifier isEqualToString:@"newCatSegue"])
    {
        UIViewController *dvc = segue.destinationViewController;
        UIPopoverPresentationController *catNewPPC = dvc.popoverPresentationController;


        NSManagedObjectContext *localContext = [NSManagedObjectContext MR_contextForCurrentThread];

        if ([[segue identifier] isEqualToString:@"newTransSegue"])
        {
            UINavigationController *navController = (UINavigationController *)segue.destinationViewController;
            AddCategoryVC *addCatVC = (AddCategoryVC *)navController.topViewController;
            addCatVC.delegate = self;
            WMMGCategory *addedCategory = (WMMGCategory *)[WMMGCategory MR_createInContext:localContext];
            addCatVC.brandNewCategory = addedCategory;
        }

        if (catNewPPC)
        {
            catNewPPC.delegate = self;
        }
    }

}

Answer 1

你的问题是你在viewDidLoad中创建了一个AddCategoryVC实例，它不是你在屏幕上拥有的实例（你从不对它做任何事情，所以它会在viewDidLoad超出范围后立即解除分配）。您需要获得对已有实例的引用。如果不知道你在哪里制作控制器以及它们如何在屏幕上显示，我就无法具体说明如何做到这一点。

委托方法在被调用时未被调用或未被触发

1 个答案: