Scrollview wrong scrolling on custom control - ios

Question

I have a custom control that looks like this:
It allows you to pick multiplier from 1 to 10. Inside it is scroll view with multiple UILabels in it. Each label has tag and using the tag I calculate needed positions for label.
The user may either swipe to move this or tap on the number to make it move automatically.
But I have faced the problem - if the view is scrolling and I tap on the number while it is scrolling, it will stop not on the number I tapped on, but on some other number.
When the scroll view is not scrolling taps work fine. Here is relevant code:
This method is needed to stop on the number when it ends scrolling:
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
NSInteger targetIndex = targetContentOffset->x / (self.frame.size.width / 4.0) ;
*targetContentOffset = CGPointMake((targetIndex) * (self.frame.size.width / 4.0), targetContentOffset->y);
if (targetIndex > [self.dataSource numberOfItemsInPicker:self] - 1) {
targetIndex = [self.dataSource numberOfItemsInPicker:self] - 1;
}
if (self.gameName) {
for (int i=0; i<self.labels.count; i++) {
UILabel *label = self.labels[i];
if (i == targetIndex) {
label.textColor = [GeneralHelper colorForGame:self.gameName];
}
else {
if ([self.delegate respondsToSelector:#selector(colorForTextForSmallNumberPicker:)]) {
label.textColor = [self.delegate colorForTextForSmallNumberPicker:self];
}
}
}
}
if (self.delegate) {
[self.delegate smallNumberPickerView:self didPickNumberAtIndex:targetIndex];
}
}
This is the code that determines position of labels in scroll view:
- (CGPoint)offsetForIndex:(NSUInteger)index
{
return CGPointMake(roundf((self.frame.size.width / 4.) * index), 0.);
}
And I think this is the offending code that handles tap gesture recognizer:
- (void)handleTapGesture:(UIGestureRecognizer *)recognizer
{
if (recognizer.state != UIGestureRecognizerStateEnded) {
return;
}
[self.scrollView setContentOffset:[self offsetForIndex:recognizer.view.tag - LABELS_START_TAG] animated:YES];
}
My ideas what happens is that during scrolling frame is wrong, or positions are wrong, but I have no idea how to handle this. I noticed that when I tap I NSLog target offset and it is wrong, and if it is not scrolling - I will get right offset.
What can I do about this?

Answer 1

There was an error in calculations. This line:
return CGPointMake(roundf((self.frame.size.width / 4.) * index), 0.);
It divided by 4 but the labels were actually smaller then 1/4 of the picker, so I got wrong results.