Question

在我的应用程序中，我正在尝试将数据从父视图传递到子视图。但是，当我运行应用程序时，没有调用委托方法。以下是我如何实现自定义委托的代码： parent.h

    @protocol SLBWallViewControllerDelegate <NSObject>

- (void) pictureToBeUploaded:(id)picture;

@end

@interface SLBWallViewController : UIViewController <UIActionSheetDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate>
- (IBAction)createPotButtonPressed:(id)sender;

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

parent.m

[self.delegate pictureToBeUploaded:info[UIImagePickerControllerEditedImage]];//i'm taking the pic from a uiimagepicker

child.h

@interface SLBPostViewController : UIViewController <SLBWallViewControllerDelegate>
@property (weak, nonatomic) IBOutlet UIImageView *picture;
@end

child.m

#pragma mark - Wall View Controller Delegate
- (void)pictureToBeUploaded:(id)picture{
    self.picture.image = picture;
}

有什么不对或丢失吗？

Answer 1

嗯，问题可能是（编辑：在评论中确认）是self.delegate此时为nil。因此，您向nil发送消息，当然没有任何反应。您要做的是确保在尝试发送消息之前将Child实例分配给delegate属性。像这样的东西：

//...
self.delegate = //.. a 'Child' instance

//...
[self.delegate pictureToBeUploaded:info[UIImagePickerControllerEditedImage]];

Answer 2

//（1）在.h文件中的Child中创建一个属性

@property（非原子，强）UIImage * someImage;

//（2）在.m文件中的Child中覆盖属性

- （void）setSomeImage：（UIImage *）someImage {

_someImage=someImage;
self.picture.image = self.someImage;

}

//（3）在.m文件中的父级中将图像设置为子级的'someImage'属性

childsObject.someImage = UIImagePickerControllerEditedImage;

将数据从父级传递给子级

2 个答案: