Question

I have a method called cache image. This uses a NSNotification centre to post the info that image has been cached. I have the data NSMutableDictionary *userInfo. I’m trying to add an observer to retrieve the image and save using the _URL as the key. The problem is both URL and image are added to the dictionary as object with their own keys. Is it possible to retrieve the image for the corresponding key?

 - (void)cacheImage:(UIImage *)image
   {
    if (!_cancelled)
    {
    if (image && _URL)
    {
        BOOL storeInCache = YES;
        if ([_URL isFileURL])
        {
            if ([[[_URL absoluteURL] path] hasPrefix:[[NSBundle mainBundle] resourcePath]])
            {
                //do not store in cache
                storeInCache = NO;
            }
        }
        if (storeInCache)
        {
            [_cache setObject:image forKey:_URL];
        }
    }
    NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                         image, AsyncImageImageKey,
                                         _URL, AsyncImageURLKey,
                                         nil];
    NSLog(@"%@",_URL);

        if (_cache)
        {
            [userInfo setObject:_cache forKey:AsyncImageCacheKey];
        }

        _loading = NO;
        [[NSNotificationCenter defaultCenter] postNotificationName:AsyncImageLoadDidFinish
                                                            object:_target
                                                          userInfo:[[userInfo copy] autorelease]];
    }
    else
    {
        _loading = NO;
        _cancelled = NO;
    }

 }

in my other class viewcontroller.m file

   -(void)ViewDidLoad{

     [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(imageLoaded:)
                                             name:AsyncImageLoadDidFinish
                                           object:nil];
    }


     - (void)imageLoaded:(NSNotification *)notification
  {

    NSMutableDictionary *imageCache = notification.object;// help needed here
   }

Im trying to add an observer , but I can’t figure how to use the object ‘_URL’ as a key for the image.After using the observer to receive the object, I have to find the imagecache for that URL.

Answer 1

You have this code now:

NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                     image, AsyncImageImageKey,
                                     _URL, AsyncImageURLKey,
                                     nil];

So when you want to add it to the imageCache:

NSURL *_url = [userInfo objectForKey:AsyncImageURLKey];
UIImage *image = [userInfo objectForKey:AsyncImageImageKey];

[imageCache setObject:image forKey:_url];