Custom UITableViewCell imageView not updating after setImage

Question

I've got a custom UITableViewCell class whose model object performs an asynchronous download of an image which is to be displayed in the cell. I know I've got the outlets connected properly in IB for WidgetTVC, I know that image data is being properly returned from my server, and I've alloc/init'd the widget.logo UIImage too. Why is the image always blank then in my tableViewCell? Thanks in advance.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    Widget *theWidget = [widgetArray objectAtIndex:indexPath.row];

    static NSString *CellIdentifier = @"WidgetCell";
    WidgetTVC *cell = (WidgetTVC*)[self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if(cell == nil)
    {
        [[NSBundle mainBundle] loadNibNamed:@"WidgetTVC" owner:self options:nil];
        cell = self.widgetTVC;
        self.widgetTVC = nil;
    }

    [cell configureWithWidget:theWidget];

    return cell;
}

In my WidgetTVC class, I have the following method:

- (void)configureWithWidget:(Widget*)aWidget {
    self.widget = aWidget;
    self.nameLbl.text = aWidget.name;
    [self.logoIvw setImage:aWidget.logo]; // logoIvw is the image view for the logo
}

Finally- I've got the callback method that sets the logo UIImage property on the Widget model object asynchronously (simplified):

 (void)didReceiveImage:(ASIHTTPRequest *)request {
    // I pass a ref to the Widget's logo UIImage in the userInfo dict
    UIImage *anImage = (UIImage*)[request.userInfo objectForKey:@"image"];      
    UIImage *newImage = [UIImage imageWithData:[request responseData]];
    anImage = newImage;
 }

Answer 1

In didReceiveImage:, you're only modifying the local pointer anImage. You need to set the image property of your UIImageView in order to update what gets displayed. Instead of stashing a reference to your widget's UIImage, pass a reference to the UIImageView, and in didReceiveImage: do something like

UIImageView *imageView = (UIImageView*)[request.userInfo objectForKey:@"imageView"]; 
UIImage *newImage = [UIImage imageWithData:[request responseData]];
imageView.image = newImage;

Answer 2

Perhaps the best solution would be to have your model object have the image as a property and the display object subscribe to the image property's changes through KVO and update itself whenever the image property changes.

Answer 3

OK- there were a couple things wrong here. Thanks to bosmacs and Ed Marty as both of your comments were used to get to the solution.

First, I added a method to the Widget object to get the logo asynchronously:

- (void)asyncImageLoad {
    ...
    // logo is a UIImage
    [AsyncImageFetch fetchImage:&logo fromURL:url];
}

And my own AsyncImageFetch class looks like this:

+ (void)fetchImage:(UIImage**)anImagePtr fromURL:(NSURL*)aUrl {     
    ASIHTTPRequest *imageRequest = [ASIHTTPRequest requestWithURL:aUrl];    
    imageRequest.userInfo = [NSDictionary dictionaryWithObject:[NSValue valueWithPointer:anImagePtr] forKey:@"imagePtr"];
    imageRequest.delegate = self;
    [imageRequest setDidFinishSelector:@selector(didReceiveImage:)];
    [imageRequest setDidFailSelector:@selector(didNotReceiveImage:)];
    [imageRequest startAsynchronous];
}

+ (void)didReceiveImage:(ASIHTTPRequest *)request {
    UIImage **anImagePtr = [(NSValue*)[request.userInfo objectForKey:@"imagePtr"] pointerValue];    
    UIImage *newImage = [[UIImage imageWithData:[request responseData]] retain];
    *anImagePtr = newImage;
}

Finally, per Ed, I added this to the configureWithWidget method that helps set up my WidgetTVC:

[aCoupon addObserver:self forKeyPath:@"logo" options:0 context:nil];

And when a change is observed, I update the imageView and call [self setNeedsDisplay]. Works like a charm. Any way I can give you both points?