Scroll UITableViewCell to visible not working as intended - ios

Question

I have a button in a UITableViewCell which is stored as an ivar called currentButton. When that button is clicked a UIView containing a UIPickerView and UIToolBar is invoked and shown from the bottom of the screen. However, I have looked at other posts for hours and this following code still doesn't work. The cells sometimes scroll down below the keyboard and the cells all the way at the bottom of the UITableView do not scroll up enough to go on top of the UIView backgroundPickerView. This is my code:
CGPoint center = currentButton.center;
CGPoint rootViewPoint = [currentButton.superview convertPoint:center toView:self.view];
NSIndexPath *indexPath = [measurementTableView indexPathForRowAtPoint:rootViewPoint];
CGRect cellRect = [measurementTableView rectForRowAtIndexPath:indexPath];
if (cellRect.origin.y + cellRect.size.height >= backgroundPickerView.frame.origin.y) {
[measurementTableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
CGPoint offset = measurementTableView.contentOffset;
offset.y += ((cellRect.origin.y - cellRect.size.height) - backgroundPickerView.frame.origin.y);
[measurementTableView setContentOffset:offset animated:YES];
}
Does anyone see what I am doing wrong here?

Answer 1

UITableViewCell are reused,keeping a reference of a UITableViewCell's subView is not a good approach.
If the special UITableViewCell is not in UITableView's visibleCells ,its frame is undefined.
A solution is:
Create a custom UITableViewCell that has the same structure as you need.
Keep a reference of the indexpath for the custom UITableViewCell.
Use this indexpath to do the work .
I hope this will work:
[measurementTableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
CGPoint offset = measurementTableView.contentOffset;
offset.y += backgroundPickerView.frame.height;

Answer 2

This code worked for me. Uses a different approach than the ones suggested here and it's good for what I need.
CGRect buttonFrame = [currentButton convertRect:currentButton.bounds toView:measurementTableView];
NSIndexPath *indexPath = [measurementTableView indexPathForRowAtPoint:buttonFrame.origin];
CGRect backPickFrame = [backgroundPickerView convertRect:backgroundPickerView.bounds toView:measurementTableView];
if (buttonFrame.origin.y + buttonFrame.size.height >= backPickFrame.origin.y) {
measurementTableView.contentInset = UIEdgeInsetsMake(0.0, 0.0, backgroundPickerView.frame.size.height, 0.0);
[measurementTableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
} else {
[measurementTableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
}

Answer 3

First problem is that UITableView is partially hidden under a keyboard. So when you trying scroll to bottom rows table will bounce back and required content is not visible.
To solve this problem when keyboard appears/hides you have two choices.
update value of self.tableView.contentInstet.bottom to take into account keyboard size
update frame of table, if you are using auto-layout then best approach will be update constant part of bottom constraint (IMO this is better approach).
After you did that you can do this:
CGRect rectToBeVisible = [currentButton convertRect: currentButton.bounds
toView: self.tableView];
[self.tableView scrollRectToVisible: rectToBeVisible animated: YES];
I could messed up view to which convertion should be performed, so experiment a bit, but general concept should be clear.