contentoffset in scrollview - iphone

Question

How can i set the contentoffset for image to track down which image user is on and selected to save it to phot album.
UIScrollView *imageScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
imageScrollView.pagingEnabled = YES;
NSInteger numberOfViews = 61;
for (int i = 0; i < numberOfViews; i++) {
CGFloat xOrigin = i * self.view.frame.size.width;
NSString *imageName = [NSString stringWithFormat:#"image%d.png", i];
_image = [UIImage imageNamed:imageName];
_imageView = [[UIImageView alloc] initWithImage:_image];
_imageView.frame = CGRectMake(xOrigin, 0, self.view.frame.size.width, self.view.frame.size.height);
UILongPressGestureRecognizer *gestureRecognizer = [[UILongPressGestureRecognizer alloc]
initWithTarget:self
action:#selector(handleLongPress:)];
imageScrollView.userInteractionEnabled = YES;
[imageScrollView addGestureRecognizer:gestureRecognizer];
gestureRecognizer.delegate = self;
[gestureRecognizer release];
[imageScrollView addSubview:_imageView];
imageScrollView.contentSize = CGSizeMake(self.view.frame.size.width * numberOfViews, self.view.frame.size.height);
Edit:
imageScrollView.contentOffset = CGPointMake(CGFloat x, CGFloat y);
in the contentoffset not sure what to put so that image can be tracked the user is on and selected to save to photo album
- (void)handleLongPress:(UILongPressGestureRecognizer*)gestureRecognizer{
if (gestureRecognizer.state == UIGestureRecognizerStateBegan){
UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:nil delegate:self cancelButtonTitle:#"Cancel" destructiveButtonTitle:nil otherButtonTitles:#"Save Photo", nil];
actionSheet.actionSheetStyle = UIActionSheetStyleBlackTranslucent;
[actionSheet showInView:self.view];
[actionSheet release];
}}
-(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
switch (buttonIndex) {
case 0:
[self savePhoto];
break;
default:
break;
}
-(void)savePhoto{
CGPoint location = [gesture locationInView:_imageView];
if (CGRectContainsPoint(_imageView.bounds, location)){
UIImageWriteToSavedPhotosAlbum(_image, self, #selector(image: didFinishSavingWithError:contextInfo:), nil);
}}}
Any ideas will be appreciated.

Answer 1

You can use this code (that comes from one of the apple sample projects for scrollview) to determine what the currently visible 'page' is in the scrollview.
// Calculate which page is visible
CGFloat pageWidth = self.scrollView.frame.size.width;
int page = floor((self.scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
Once you know this index number you can use it to determine what image to save