Objective-C Definedness

Posted by Dan Ray on Stack Overflow See other posts from Stack Overflow or by Dan Ray
Published on 2010-05-12T12:57:11Z Indexed on 2010/05/12 13:04 UTC
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This is an agonizingly rookie question, but here I am learning a new language and framework, and I'm trying to answer the question "What is Truth?" as pertains to Obj-C.

I'm trying to lazy-load images across the network. I have a data class called Event that has properties including:

@property (nonatomic, retain) UIImage image;
@property (nonatomic, retain) UIImage thumbnail;

in my AppDelegate, I fetch up a bunch of data about my events (this is an app that shows local arts event listings), and pre-sets each event.image to my default "no-image.png".

Then in the UITableViewController where I view these things, I do:

if (thisEvent.image == NULL) {
    NSLog(@"Going for this item's image");
    UIImage *tempImage = [UIImage imageWithData:[NSData dataWithContentsOfURL:
                  [NSURL URLWithString:
                    [NSString stringWithFormat:
                    @"http://www.mysite.com/content_elements/%@_image_1.jpg",
                              thisEvent.guid]]]];
    thisEvent.image = tempImage;

}

We never get that NSLog call. Testing thisEvent.image for NULLness isn't the thing. I've tried == nil as well, but that also doesn't work.

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