UIImageView更改问题iPhone问题

Question

I am trying to make a button in my IPhone app which changes an existing image (simple, I know! but I've spent 2 days on this :)

I have a button:

- (IBAction)myButton {  
    myUIImageView.image = [UIImage imageNamed:@"image.jpg"];
    NSLog(@"my button");
}

I am attempting to find out why the button is not doing anything. "my button" does get logged to the console so I know its mapped correctly. Firstly, I was hoping someone could tell me if I could perhaps log some more important info here, like the image file path? Or perhaps you see why this isn't working.

I synthesize myUIImageView above this:

@synthesize myUIImageView;

And I declare it in my .h file:

- (IBAction)myButton;
    @property(retain, nonatomic) IBOutlet UIImageView* myUIImageView;

Answer 1

Typically, something is nil here.

You have

myUIImageView.image = [UIImage imageNamed:@"image.jpg"];

So the obvious suspects would be either:

1. myUIImageView is nil, or
2. [UIImage imagedNamed:@"image.jpg"] is returning nil.

Add some logging to see if either of those is true.

NSLog(@"imageView: %@, image resource: %@", myUIImageView, [UIImage imageNamed:@"image.jpg"]);

If the image isn't being loaded, then I would expect for you to see a change in the UI, so that's probably not the issue.

More likely is that the nib outlet for myUIImageView haven't been wired up correctly in Interface Builder, but the logging should point you in the right direction.

Answer 2

Two things to try:

1. Make sure that your UIImageView is actually being displayed. Do do this, just set its background color to something visible, eg, myUIImageView.backgroundColor = [UIColor redColor]; .
2. Make sure that your image file ("image.jpg") is part of your project.