ios - 从 Parse iOS 下载图像

Question

我正在编写一个允许用户在 Parse 上拍摄和存储图像的应用程序。到目前为止，我已经设法通过使用以下逻辑将图像数组保存到 Parse:

• 拍照
• 将对象添加到数组
• 将数组转换为 NSData
• 将 NSData 转换为 PFFile
• 设置文件上传目的地(通过唯一的objectId)
• 上传 PFFile 进行解析

这就是代码的样子；请原谅它现在在 dismissViewController 中，我只是想让它成功保存:

- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
_takenImage = (UIImage *) [info objectForKey:UIImagePickerControllerOriginalImage];
[self dismissViewControllerAnimated:YES completion:^
{
    // Add object to array: Working
    [_tankImagesArray addObject:_takenImage];
    NSLog(@"Number of images taken: %lu", (unsigned long)_tankImagesArray.count);

    // Convert array to NSData Object
    NSData *imageData = [NSKeyedArchiver archivedDataWithRootObject:_tankImagesArray];

    // Convert NSData Object to PFFile
    PFFile *imageFile = [PFFile fileWithData:imageData];

    PFQuery *tankQuery = [PFQuery queryWithClassName:@"SavedTanks"];
    _tankObject = [tankQuery getObjectWithId:_passedValue];

    [_tankObject setObject:imageFile forKey:@"tankImages"];

    [_tankObject save];
}];
}

现在，我的问题是:我究竟应该如何检索该文件？我的最终目标是允许用户查看他们过去拍摄的图像，并将其添加到集合中的图片列表中并将它们上传到服务器。我只是不确定如何在上传文件后检索文件并确保保持完整性。

Answer 1

你试过吗:

PFQuery *query = [PFQuery queryWithClassName:@"SavedTanks"];
[query whereKey:@"tankImages" equalTo:@"your_image.jpg"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
  if (!error) {
    // The find succeeded.
    NSLog(@"Successfully retrieved %d images.", objects.count);
    // Do something with the found objects
    for (PFObject *object in objects) {
        NSLog(@"%@", object.objectId);
    }
  } else {
    // Log details of the failure
    NSLog(@"Error: %@ %@", error, [error userInfo]);
  }
}];