How can I change the image displayed in a UIImageView programmatically?

If you have an IBOutlet to a UIImageView already, then all you have to do is grab an image and call setImage on the receiver (UIImageView). Two examples of grabbing an image are below. One from the Web, and one you add to your Resources folder in Xcode.

UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://farm4.static.flickr.com/3092/2915896504_a88b69c9de.jpg"]]];

or

UIImage *image = [UIImage imageNamed: @"cell.png"];

Once you have an Image you can then set UIImageView:

[imageView setImage:image];

The line above assumes imageView is your IBOutlet.

That's it! If you want to get fancy you can add the image to an UIView and then add transitions.

P.S. Memory management not included.

Note that the NIB file doesn't wire up all the IBOutlets until the view has been added to the scene. If you're wiring things up manually (which you might be doing if things are in separate NIBs) this is important to keep in mind.

So if my test view controller has an "imageView" wired by a nib, this probably won't work:

  testCardViewController.imageView.image = [UIImage imageNamed:@"EmptyCard.png"];  [self.view addSubview:testCardViewController.view];

But this will:

  [self.view addSubview:testCardViewController.view];  testCardViewController.imageView.image = [UIImage imageNamed:@"EmptyCard.png"];

This worked for me

[ImageViewName setImage:[UIImage imageNamed: @"ImageName.png"]];

Make sure that the ImageView is declared properly in the .h file and is linked with the IB element.