Schedule::obtainShiftByPrimary

public function obtainShiftByPrimary($shiftId)
{
	if (!$this->obtainShifts() || !$shiftId)
	{
		return null;
	}
	foreach ($this->obtainShifts() as $shift)
	{
		if ($shift->getId() === (int)$shiftId)
		{
			return $shift;
		}
	}
	return null;
}