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

Question

I have an IBOutlet to an UIImageView, but when I look at the UIImageView doc, I can't see any hint about how to programmatically change it. Do I have to fetch an UIImage object from that UIImageView?

Answer 1

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.

Answer 2

Following Jordan's advice (which should work actually), try to set the UIImageView to be visible:

[imageView setHidden: NO];

and also - don't forget to attach it to the main UIView:

[mainView addSubview: imageView];

and to bring to the front:

[mainView bringSubviewToFront: imageView];

Hope combining all these steps will help you solve the mystery.

Answer 3

This worked for me

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

Make sure the image that you wish to change it to is in the resources folder. And that the image view is declared properly in the .h file and is linked with the IB element.

Answer 4

For the purpose of people who may be googling this to try to solve their problem, remember to properly declare the property in your header file and to synthesize the UIImageView in your implementation file... It'll be tough to set the image programmatically without getter and setter methods.

#import <UIKit/UIKit.h>

@interface YOURCONTROLLERNAME : UIViewController {
    IBOutlet UIImageView *imageToDisplay;
}

@property (nonatomic, retain) IBOutlet UIImageView *imageToDisplay;

@end

and then in your .m :

@implementation YOURCONTROLLERNAME

@synthesize imageToDisplay;
//etc, rest of code goes here

From there you should be fine using something like the following to set your image.

[YOURCONTROLLER.counselorImage setImage:[UIImage imageNamed:value]];

Answer 5

Thank you, Adi! Your note re: setHidden solved the problem for me!! If I weren't so new to the forum, I'd give you a vote up!

Answer 6

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"];