背景

我的应用程序的一部分使用UIImagePicker获取图像，并使用CoreData将它们保存到磁盘。所述图像与模型中的活动相关联。活动与图像有一对多的关系。

我需要在捕获后立即将图像保存到磁盘，然后将其故障排除内存，保留缩略图以供显示。如果不这样做，iOS会在捕获相对较少数量的图像后使用太多内存来杀死我的应用程序。

我将Thumbnails设为一个单独的实体，以避免在我需要的只是缩略图的情况下将整个图像带入内存。缩略图与图像具有一对一的关系。此外，由于各种原因，我没有使用核心数据来存储缩略图图像数据;相反，我存储文件名，并自己管理磁盘上的文件。

所有这些意味着，如果用户在添加了至少一个图像后取消添加活动，则需要删除用户添加的图像和缩略图。

问题

当我尝试删除添加的图像对象时，会发生两件事。首先，Core Data抱怨我的删除规则：

Core Data: annotation: repairing missing delete propagation for to-one relationship image on object <Thumbnail: 0x1dd4d9e0> (entity: Thumbnail; id: 0x1dd4d410 <x-coredata:///Thumbnail/tE7E99D89-C986-4287-ABBD-C6BA7006E9264> ; data: {
    activity = nil;
    fileName = "ECD70C72-745A-4959-BF41-586E9521F1D6";
    image = "0x1dd9f960 <x-coredata:///Image/tE7E99D89-C986-4287-ABBD-C6BA7006E9263>";
}) with bad fault 0x1dd9f960 <x-coredata:///Image/tE7E99D89-C986-4287-ABBD-C6BA7006E9263>

其次，当我尝试保存托管对象上下文时，保存失败，Core Data引发异常。这是NSError对象的输出：

Error Domain=NSCocoaErrorDomain Code=134030 "The operation couldn’t be completed. (Cocoa error 134030.)"
 UserInfo=0x1f0ca270 {NSAffectedObjectsErrorKey=(
    "<Image: 0x1dd9f910> (entity: Image; id: 0x1dd9f960 <x-coredata:///Image/tE7E99D89-C986-4287-ABBD-C6BA7006E9263> ;
         data: {
             activity = nil;
             image = nil;
             thumbnail = nil;
         })"
), NSUnderlyingException=Cannot delete object that was never inserted.}

SO。显然我正在尝试删除一个我从未插入的对象？只有我很确定我做到了。

关系详情

活动＆lt; 1 - *＆gt;图片;删除规则：级联
- ＆GT;反转：图像＆lt; 1-1＆gt;活动;删除规则：nullify

图像＆lt; 1-1＆gt;缩略图;删除规则：级联
- ＆GT;反转：缩略图＆lt; 1-1＆gt;图片;删除规则：nullify

相关代码

图像采集：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage* acquiredImage = (UIImage*)info[UIImagePickerControllerEditedImage];
    if (!acquiredImage)  {
        acquiredImage = (UIImage*)info[UIImagePickerControllerOriginalImage];
    }

    // Save the image to disk so we can fault it and free up its memory
    NSManagedObjectContext* moc = [(ATAppDelegate*)[[UIApplication sharedApplication] delegate] managedObjectContext];
    Image* imageToSave = [NSEntityDescription insertNewObjectForEntityForName:@"Image" inManagedObjectContext:moc];
    Thumbnail* thumbToSave = [NSEntityDescription insertNewObjectForEntityForName:@"Thumbnail" inManagedObjectContext:moc];
    [addedImageManagedObjects addObject:imageToSave];
    [addedThumbnailManagedObjects addObject:thumbToSave];

    [thumbToSave setThumbnailImage:acquiredImage];
    imageToSave.thumbnail = thumbToSave;

    NSError* error;
    [moc save:&error];
    // TODO: error handling

    // I know it doesn't look it, but this call will turn the imageToSave into a fault, thus freeing up its memory
    [moc refreshObject:imageToSave mergeChanges:NO];

    // NOW, we can add the thumbnail image to our collection view
    // NOTE, -thumbnailImage is a method on my Thumbnail NSManagedObject subclass
    [self addImage:[thumbToSave thumbnailImage] toCollectionView:imageDisplayView];

    [self dismissModalViewControllerAnimated:YES];
}

取消处理程序：

- (IBAction)cancel:(id)sender {
    NSManagedObjectContext* moc = [(ATAppDelegate*)[[UIApplication sharedApplication] delegate] managedObjectContext];

    // Delete any images we saved to disk
    // Note that the activity object's changes get discarded b/c they were made on the child managed object context
    // (We couldn't do that for images b/c we needed them to be written to disk and then faulted out of memory)
    for (Thumbnail* thumb in addedThumbnailManagedObjects)  {
        // This method deletes the thumbnail image file whose storage I am managing myself
        [thumb deleteThumbnailFile];
        // I shouldn't have to explicitly delete the thumbnail since the delete of its image should cascade down...right?
    }
    for (Image* image in addedImageManagedObjects)  {
        [moc deleteObject:image];
    }

    NSError* error;
    if (![moc save:&error])  {
        NSLog(@"%@", error);
    }
    // TODO: error handling

    [self resetToPristineState];
    [self.presentingViewController dismissModalViewControllerAnimated:YES];
}

摘要

我无法看到我出错的地方，而且我收到的错误消息没有帮助。更糟糕的是，谷歌搜索错误消息并没有给我任何有用的结果。因此，我向你们提供了很有经验的人帮忙。

Answer 1

喔。天啊。这个错误太愚蠢了。我很惭愧。

好。请注意，在我的图像采集处理程序中，我从未设置图像管理对象的图像数据？是啊。事实证明你需要这样做。：）

无论如何，我已经解决了自己的问题。

核心数据无法删除从未插入的对象错误

背景

问题

关系详情

相关代码

摘要

1 个答案: