Get focused (closest to the picker's vertical center) row in UIPickerView

gistfile1.m

/**
 *  Returns focused (closest to the picker's vertical center) row.
 *
 *  @param picker    picker which rows should be inspected
 *  @param row       center row to search around (row +- some_value) will be evaluated
 *  @param component component in picker to be inspected
 *
 *  @note This approach requires use of -pickerView:viewForRow:forComponent:reusingView: for row creation, if you
 *        only use -pickerView:titleForRow:forComponent:, it won't be able to get views via -viewForRow:forComponent:
 *        and inspect them.
 *        This method should be called when all the views for rows are loaded, i.e. if you call it before you return 
 *        a view (say, in -pickerView:titleForRow:forComponent:) it can fail and return -1.
 *
 *  @return Focused row or -1 if it can not find it.
 */
- (NSInteger)pickerView:(UIPickerView *)picker focusedRowAroundRow:(NSInteger)row inComponent:(NSInteger)component
{
    NSInteger dispersion = 20; // row +- dispersion
    NSInteger fromRow = row - dispersion;
    NSInteger toRow = row + dispersion;
    NSInteger numberOfRows = [picker numberOfRowsInComponent:component];

    if(fromRow < 0) fromRow = 0;
    if(toRow >= numberOfRows) toRow = numberOfRows - 1;

    NSInteger currentSelectedRow = -1;
    UIView *currentSelectedRowPretendentView = nil;
    CGFloat minDY = CGFLOAT_MAX;
    CGFloat dy = 0;
    UIView *currentView = nil;
    CGPoint pickerBoundsCenter = CGPointMake(CGRectGetMidX(picker.bounds), CGRectGetMidY(picker.bounds));

    // get vertically center-most view
    for(NSInteger irow = fromRow; irow <= toRow; irow++)
    {
        currentView = [picker viewForRow:irow forComponent:component];
        if(currentView)
        {
            CGPoint centerInPicker = [currentView convertPoint:CGPointMake(CGRectGetMidX(currentView.bounds),
                                                                           CGRectGetMidY(currentView.bounds))
                                                        toView:picker];

            dy = fabs(centerInPicker.y - pickerBoundsCenter.y);
            if(dy < minDY)
            {
                minDY = dy;
                currentSelectedRow = irow;
                currentSelectedRowPretendentView = currentView;
            }
        }
    }


    // if pretendent's row dy is bigger then it's height it should not be selected
    if(minDY > currentSelectedRowPretendentView.bounds.size.height)
    {
        currentSelectedRow = -1;
    }

    return currentSelectedRow;
}