Question

我得到了下一个问题我有3个视图（UITableView和2 View Controller）我制作了下两个协议：AddViewControllerDelegate和ViewAlarmControllerDelegate： AddViewController.h：

@protocol AddViewControllerDelegate <NSObject>

- (void)addAlarm:(AlarmObject *)alarm;

@end

@interface AddViewController : UIViewController
{
    id <AddViewControllerDelegate> delegate;
}
@property (retain) id delegate;

ViewAlarmController.h：

@protocol ViewAlarmControllerDelegate <NSObject>

- (void)changeAlarm:(AlarmObject *)alarm atIndex:(int) alarmID;
- (void)deleteAlarmAtIndex:(int) alarmID;

@end

@interface ViewAlarmController : UIViewController
{
    id <ViewAlarmControllerDelegate> delegate;
}

@property (retain) id delegate;

然后在HomeViewController.h中导入为fallow：

#import "AddViewController.h"
#import "ViewAlarmController.h"
#import "AlarmObject.h"
@interface HomeViewController : UITableViewController <AddViewControllerDelegate, ViewAlarmControllerDelegate>

我在HomeViewController.m中有下一个方法声明

- (void)addAlarm:(AlarmObject *)alarm{
    [self.items addObject:alarm];
    [self.tableView reloadData];
    NSLog (@"added");
}

- (void)deleteAlarmAtIndex:(int)alarmID{
    NSLog(@"alarmID: %d", alarmID);
    [self.items removeObjectAtIndex:alarmID];
    NSLog(@"items: %@", items);
    [self.tableView reloadData];
}

- (void)changeAlarm:(AlarmObject *)alarm atIndex:(int)alarmID{
    NSLog(@"change");
}

ViewAlarmController.m调用协议的方法代码块：

- (IBAction)save:(id)sender {
    AlarmObject* alarmObj = [[AlarmObject alloc]init];
    if(![self.alarmNameField.text isEqual: @""]){
        [alarmObj setValue:self.alarmNameField.text forKey:@"alarmName"];
        NSLog (@"change alarm id = %d", alarmID);
        [self.delegate changeAlarm:alarmObj atIndex:alarmID];
    }
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (IBAction)reverse:(id)sender {
    alarmNameField.text = [alarm valueForKey:@"alarmName"];
}

- (IBAction)deleteAlarm:(id)sender {
    NSLog (@"delete alarm id: %d",alarmID);
    [self.delegate deleteAlarmAtIndex:alarmID];
    [self dismissViewControllerAnimated:YES completion:nil];
}

问题是addAlarm有效，但当我进入ViewAlarm并按下按钮删除或保存更改时，不会调用deleteAlarmAtIndex和changeAlarm方法。

问题出在下一个方法中：

 - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
    if ([segue.identifier isEqualToString:@"addAlarmSegue"]){
        AddViewController *avc = segue.destinationViewController;
        avc.delegate = self;
    }else if ([segue.identifier isEqualToString:@"viewAlarmSegue"]){
        NSIndexPath *selectedRowIndex = [self.tableView indexPathForSelectedRow];
        ViewAlarmController *vac = segue.destinationViewController;
        [vac getObject:[self.items objectAtIndex:selectedRowIndex.row] withId:selectedRowIndex.row];

        vac.delegate = self;
    }
}

我没有写vac.delegate = self;

Answer 1

确保符合您协议的对象不是nil

My1Object *a = [My1Object new];
My2Object <Myprotocol> *b = [My2Object new];

a.delegate = b;

@interface My1Object <MyProtocol> 

@property (nonatomic, weak /* or 'unsafe_unretained' for iOS less than 5.0*/) id <MyProtocol> delegate;

@end

@implementation My1Object

...



 - (void)somethingHappened {
     // just for check as I said:
     NSLog(@"self.delegate = %@", self.delegate); // make sure this is not nil!
     if ([self.delegate respondsToSelector:@selector(myProtocolMethod:)]) {
         [self.delegate myProtocolMethod:self];
     }
 }

...

@end

请记住，你不应该保留（强）你的代表！

不调用协议中的方法

1 个答案: