How to reload my view in iOS - iphone

Question

I have a imageView embedded in a scrollView. The imageView needs to be downloaded from the Internet (through flickr api), so I add a thread to handle this. But what am I supposed to do after I finished downloading the image? How can I reload my imageView?Here's my code.
In fact, it is working fine. but the imageView's size is (0, 0). How can I fix that?
- (void)viewDidLoad
{
[super viewDidLoad];
if (!self.myImage)
{
UIActivityIndicatorView* spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
[spinner startAnimating];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:spinner];
dispatch_queue_t downloadQueue = dispatch_queue_create("flickr downloader (photo)", NULL);
dispatch_async(downloadQueue, ^{
NSData* data = [NSData dataWithContentsOfURL:[FlickrFetcher urlForPhoto:self.photo format:FlickrPhotoFormatLarge]];
dispatch_async(dispatch_get_main_queue(), ^{
self.myImage = [UIImage imageWithData:data];
[self.imageView setImage:self.myImage];
[self viewDidLoad];
[self viewWillAppear:NO];
NSLog(#"imageViewSet!");
self.navigationItem.rightBarButtonItem = nil;
});
});
dispatch_release(downloadQueue);
}
else
{
NSString* imageTitle;
if ([[self.photo objectForKey:#"title"] length] > 0)
imageTitle = [self.photo objectForKey:#"title"];
else if ([[self.photo valueForKeyPath:#"description._content"] length] > 0)
imageTitle = [self.photo valueForKeyPath:#"description._content"];
else imageTitle = #"Unknown";
[[self navigationItem] setTitle:imageTitle];
self.scrollView.delegate = self;
self.scrollView.contentSize = self.imageView.image.size;
}
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
double scale = self.imageView.bounds.size.width * 1.0 / self.myImage.size.width;
if (scale > self.imageView.bounds.size.height * 1.0 / self.myImage.size.height)
scale = self.imageView.bounds.size.height * 1.0 / self.myImage.size.height;
NSLog(#"imgview%g, %g",self.imageView.bounds.size.width, self.imageView.bounds.size.height);
NSLog(#"img%g, %g",self.myImage.size.width, self.myImage.size.height);
self.imageView.frame = CGRectMake(0, 0, self.imageView.image.size.width, self.imageView.image.size.height);
[self.scrollView setZoomScale:scale];
}

Answer 1

The usual way is to call:
[self.imageView setNeedsDisplay];
Edited to Add:
I just realized you said the image view is still (0,0). From the docs :
Setting the image property does not change the size of a UIImageView.
Call sizeToFit to adjust the size of the view to match the image.