异步下载后将UIImage保存到核心数据或图像路径中

Question

I have an api which gets data, including an Image url from an api and store the data in Core Data.

I am using AFNetworking to get the data asynchronously with no issues.

However, I now need to prefetch the image and store the UIImage or its local path in CoreData instead of the remote url.

I have subclassessed AFHTTPSessionManager and use:

    return [self POST:urlPath parameters:parameters success:^(NSURLSessionDataTask * __unused task, id JSON) {

    NSArray *postsFromResponse = JSON;
    if([postsFromResponse count] > 0)
    {
        for (NSDictionary *resp in postsFromResponse)
        {

            gotResponse = YES;
            NSNumber *Id = [resp valueForKey:@"Id"];
            NSString  *imageUrl = [resp valueForKey:@"url"];

            Post*info = [self getPostWithId:Id];

                if (!info)
                {
                    info = (Post*)[NSEntityDescription insertNewObjectForEntityForName:@"Post" inManagedObjectContext:self.managedObjectContext];

                }
                info.imageUrl = imageUrl;

               .....
        }
}

I now need to asynchronously get the image and either store it locally and store the path in the Entity or store the UIImage in the Entity. The saving/storing is not an issue apart from getting a handle to the Correct Entity object after the call block.

I thought about using AFNetworking + UIImage and adding:

NSURL *url = [[NSURL alloc] initWithString:@"myUrl"]];
[info.image setImageWithURL:url placeholderImage:[UIImage imageNamed:@"placeholder"]];

However, if I want to store it locally, I need to use the call back method this but I don't know how to get the correct Entity.

I want to do:

__weak Post* weakPost = info;
[info.image setImageWithURLRequest:request placeholderImage:placeholderImage success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

 .... NSString *path = "....save UIIMage and get local path"
   weakPost.imagePath = path;

} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
 }];

But it is not storing it in the correct Entity when there are multiple posts being iterated through.

Does anyone have a steer in the right direction?

Answer 1

My suggestion: don't use a reference to the existing entity object inside your callback block. Instead, pass an identifier of the entity to the block. Inside the block you retrieve the entity object from your local database, based on the identifier, update its image url and save it.