Two nitpicks.

1. centerPoint is misleading, as you're calculating the bottom left position of the string. So `point` is fine as a name
2. The padding should not be included in the calculation like that. If you're centring something you most likely don't need to include the padding into it.

Should be fine as: `rect.origin.x + roundf((rect.size.width - stringSize.width) * 0.5f)`. If there's supposed to be left padding, you should be subtracting 2 padding? maybe?