ios - 在核心数据的库中保存和获取多个图像选择

Question

我正在构建一个项目，我在其中使用 ELCImagepickerController 进行多项选择，然后将这些选定的图像保存到核心数据中。现在我在另一个 VC 中获取这些图像并将它们显示到 UICollectionView 中。

但我在这里面临的问题是图像在 collectionView 中没有正确显示。我有两个困惑。

• 图像是否正确保存到核心数据中。
• 如果图片已保存，则是否正确获取。

这里我将选定的图像输入到核心数据中

- (void)imagePicker:(SNImagePickerNC *)imagePicker didFinishPickingWithMediaInfo:(NSMutableArray *)info
{

    _arrImages = [[NSMutableArray alloc]init];
    _imgdata = [[NSMutableData alloc]init];
    AppDelegate* app=(AppDelegate*)[[UIApplication sharedApplication]delegate];
    NSManagedObjectContext *context = app.managedObjectContext;

    Albums *objPhotos = (Albums *)[NSEntityDescription insertNewObjectForEntityForName:@"Albums" inManagedObjectContext:context];

//get images
    for (int i = 0; i < info.count; i++) {
        ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];
        [assetLibrary assetForURL:info[i] resultBlock:^(ALAsset *asset) {
        UIImage *image = [UIImage imageWithCGImage:[asset aspectRatioThumbnail]];
         _imageData = [NSData dataWithData:UIImagePNGRepresentation(image)];
        [objPhotos setPhotosInAlbum:self.imageData];



    } failureBlock:^(NSError *error) {     }];
}
 NSError * err = nil;
[context save:&err];


if (![context save:&err]) {
    NSLog(@"Can't Save! %@ %@", err, [err localizedDescription]);
}
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Success!!" message:@"Photos Successfully Selected!" delegate:self cancelButtonTitle:@"DONE" otherButtonTitles:nil];
[alert show];

} 

我在这里获取那些选定的图像

-(NSArray *)getMenCategoryList
{
    AppDelegate* app=(AppDelegate*)[[UIApplication sharedApplication]delegate];
    NSManagedObjectContext *moc=app.managedObjectContext;
    NSFetchRequest *fetch = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity =  [NSEntityDescription entityForName:@"Albums" inManagedObjectContext:moc];
    [fetch setEntity:entity];
    NSError *error;
    NSArray *result = [moc executeFetchRequest:fetch error:&error];
    if (!result) {
        return nil;
    }
    return result;
}

我在 - (NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section 中调用获取函数并返回数组计数

- (NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{

    return [[self getMenCategoryList] count];
}

最后，在此处将图像填充到 collectionView 中

- (UICollectionViewCell *) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
     UICollectionViewCell *cell = (UICollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:@"albumCollectionViewCellCell" forIndexPath:indexPath];



    Photos *objAlbumPhotos = (Photos *)[[self getMenCategoryList] objectAtIndex:indexPath.row];

    UIImage *albumImg = [UIImage imageWithData:[objAlbumPhotos valueForKey:@"photosInAlbum"]];
    UIImageView *photosimageview = (UIImageView *)[cell.contentView viewWithTag:1];
    photosimageview.image = albumImg;



    return cell;
}

非常感谢任何帮助。

Answer 1

注意:我只是编辑您的代码，请先根据您的代码确认，然后根据您的要求进行编辑

第 1 步:生成唯一的文件名并将图像以该文件名保存到您的文件路径。
步骤 2:成功写入文件后，将该路径保存到核心数据。
步骤3:为了获取，使用核心数据路径从目录中获取图像。

- (NSString*)generateFileNameWithExtension:(NSString *)extensionString {
        // Extenstion string is like @".png"

        NSDate *time = [NSDate date];
        NSDateFormatter* df = [NSDateFormatter new];
        [df setDateFormat:@"dd-MM-yyyy-hh-mm-ss"];
        NSString *timeString = [df stringFromDate:time];
        int r = arc4random() % 100;
        int d = arc4random() % 100;
        NSString *fileName = [NSString stringWithFormat:@"File-%@%d%d%@", timeString, r , d , extensionString ];

        NSLog(@"FILE NAME %@", fileName);

        return fileName; 
}



 - (void)imagePicker:(SNImagePickerNC *)imagePicker didFinishPickingWithMediaInfo:(NSMutableArray *)info
    {

        _arrImages = [[NSMutableArray alloc]init];
        _imgdata = [[NSMutableData alloc]init];
        AppDelegate* app=(AppDelegate*)[[UIApplication sharedApplication]delegate];
        NSManagedObjectContext *context = app.managedObjectContext;

        Albums *objPhotos = (Albums *)[NSEntityDescription insertNewObjectForEntityForName:@"Albums" inManagedObjectContext:context];

    //get images
        for (int i = 0; i < info.count; i++) {
            ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];
            [assetLibrary assetForURL:info[i] resultBlock:^(ALAsset *asset) {
            UIImage *image = [UIImage imageWithCGImage:[asset aspectRatioThumbnail]];
             _imageData = [NSData dataWithData:UIImagePNGRepresentation(image)];

    NSString *strfilename = [self generateFileNameWithExtension:@".jpg"];


    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *filePath =  [documentsDirectory stringByAppendingPathComponent:strfilename];

            [_imageData writeToFile:filePath atomically:YES];

           [objPhotos setPhotosInAlbum:filePath];

        } failureBlock:^(NSError *error) {     }];
    }
     NSError * err = nil;
    [context save:&err];


    if (![context save:&err]) {
        NSLog(@"Can't Save! %@ %@", err, [err localizedDescription]);
    }
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Success!!" message:@"Photos Successfully Selected!" delegate:self cancelButtonTitle:@"DONE" otherButtonTitles:nil];
    [alert show];

    }