UIImageView.image Not Receiving Value of UIImage - ios

Question

I'm having difficulties assigning the value of an image to an image view image. I've tested that the source image has a value at the time of assignment to the image view image, and indeed it does. However, the assignment just does't appear to happen, and the image view image remains null. Can anyone help me with what I'm doing wrong?
Thanks.
- (void)viewDidLoad {
[super viewDidLoad];
self.scrollView.contentSize = self.imageView.image.size;
self.scrollView.delegate = self;
self.scrollView.minimumZoomScale = 1.0;
self.scrollView.maximumZoomScale = 100.0;
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
NSString *imageName = #"http://my.domain.com/image.png";
UIImage *img = [[UIImage alloc] init];
NSURL *imageURL = [NSURL URLWithString:imageName];
[self.activityIndicator startAnimating];
NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
img = [UIImage imageWithData:imageData];
dispatch_async(dispatch_get_main_queue(), ^{
self.imageView.image = img;//img HAS a value, but self.imageView.image does NOT receive it
[self.activityIndicator stopAnimating];
[self.imageView setNeedsDisplay];
});
});
}

Answer 1

I think problem with UIImage. where you alloc object of UIImage. Try This :
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
[self.activityIndicator startAnimating];
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:#"http://techbeasts.com/wp-content/uploads/2014/04/Wallpaper-HD.jpg"]]; // Your image URL. First check it in browser image is there.
dispatch_async(dispatch_get_main_queue(), ^{
self.imageView.image = [UIImage imageWithData:imageData];//img HAS a value, but self.imageView.image does NOT receive it
[self.activityIndicator stopAnimating];
[self.imageView setNeedsDisplay];
});
});

Answer 2

The problem is that, you have to use dispatch_async and dispatch_sync pair. So the the inner block will wait till the outer block completes its execution and downloads image.
dispatch_async(queue, ^{
NSString *imageName = #"http://my.domain.com/image.png";
UIImage *img = [[UIImage alloc] init];
NSURL *imageURL = [NSURL URLWithString:imageName];
[self.activityIndicator startAnimating];
NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
img = [UIImage imageWithData:imageData];
dispatch_sync(dispatch_get_main_queue(), ^{
self.imageView.image = img;//img HAS a value, but self.imageView.image does NOT receive it
[self.activityIndicator stopAnimating];
[self.imageView setNeedsDisplay];
});
});
Then make sure the imageView is allocated with either by programmatically or using IB.

Answer 3

The outlet had not properly connected. Reconnecting it solved the issue.