iPhone UIScrollView - how to get an image title

Question

I'm ATTEMPTING to learn UIScrollview using Apple's Docs and their sample code http://developer.apple.com/iphone/library/samplecode/Scrolling/index.html but something SO simple is escaping me.

How do you tell what image is currently on the screen, so that if I selected one of the images in the horizontal scrolling view, how would I get the filename of the image, or even a pointer in the array, to then do something further with the image.

I thought with Page Control enable I might be able to find a page # and map it to the image. I thought about counting deceleration to count pages, but a flick no full enough will increment it and give a false number.

The last thing I could think of is to get contentOffSet and divide by image size which will give a 1, 2, 3 and I could point to the array (too tired to try tonight... thought I might ask before I waste a lot more time ;-) ).

Any other ideas? I thought their'd be a method somewhere that they use in the photo album app.

Thanks for your help! Maybe I'm just not understanding their code.

Paul

PS: Here's the code:

- (void)layoutScrollImages

{ UIImageView *view = nil; NSArray *subviews = [scrollView1 subviews];

// reposition all image subviews in a horizontal serial fashion
CGFloat curXLoc = 0;
for (view in subviews)
{
    if ([view isKindOfClass:[UIImageView class]] && view.tag > 0)
    {
        CGRect frame = view.frame;
        frame.origin = CGPointMake(curXLoc, 0);
        view.frame = frame;

        curXLoc += (kScrollObjWidth);
    }
}

// set the content size so it can be scrollable
[scrollView1 setContentSize:CGSizeMake((kNumImages * kScrollObjWidth), [scrollView1 bounds].size.height)];

}

(void)viewDidLoad { self.view.backgroundColor = [UIColor viewFlipsideBackgroundColor];

// 1. setup the scrollview for multiple images and add it to the view controller // // note: the following can be done in Interface Builder, but we show this in code for clarity [scrollView1 setBackgroundColor:[UIColor blackColor]]; [scrollView1 setCanCancelContentTouches:NO]; scrollView1.indicatorStyle = UIScrollViewIndicatorStyleWhite; scrollView1.clipsToBounds = YES; // default is NO, we want to restrict drawing within our scrollview scrollView1.scrollEnabled = YES;

// pagingEnabled property default is NO, if set the scroller will stop or snap at each photo // if you want free-flowing scroll, don't set this property. scrollView1.pagingEnabled = YES;

// load all the images from our bundle and add them to the scroll view //NSUInteger i; for (i = 1; i <= kNumImages; i++) { NSString *imageName = [NSString stringWithFormat:@"Card %d.png", i]; UIImage *image = [UIImage imageNamed:imageName]; UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
```
// setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
CGRect rect = imageView.frame;
rect.size.height = kScrollObjHeight;
rect.size.width = kScrollObjWidth;
imageView.frame = rect;
imageView.tag = i;  // tag our images for later use when we place them in serial fashion
[scrollView1 addSubview:imageView];
[imageView release];
```
}

[self layoutScrollImages]; // now place the photos in serial layout within the scrollview

Unknown Unknown · Accepted Answer · 2009-06-06T21:43:22

This was easy after a good sleep!

CGPoint p = scrollView1.contentOffset;
NSLog(@"x = %f, y = %f", p.x, p.y);

Now just divide by 320 (if horizontal and full screen image) and add 1 (because it starts at 0).

Hope this helps someone else!

Paul

iPhone UIScrollView - how to get an image title

1 Answers