Space can be shared and people invited from within the space as well, to do that please tap on the collaboration icon located in the button left corner. If space has not been shared before, newly opened window will ask you to invite new people straight away, and forward you to Invite To Space window. If space has been shared before, then by taping on the collaboration icon Activity Stream and Chat will be activated, right above those you will see users who already have access and option to add new users by tapping on “+” sign.
There is also another way to share space from
within the space. When you add task list you have option to set up a due date
and to assign that task to someone, by assigning task to new team member it
will automatically share that space with him/her.