Is there a way to make sure a for loop has finished before running the next function?

I have a scenario where the user is presented with a list of users, they can select an X number of these users and once they press 'Done' for each user that has been selected I call a REST API service to get some more information on the selected user to add to the 'users' array.

But what's happening is whatever I place after the for loop seems to run before it has finished and therefore there are users missing from it

Sample code below:

function doCreateStory() {

    var users = [];



    // Add logged in user as creator

    users.push({

        id : user_id,

        creator : true

    });



    // Add all checked users

    for (var i = 0, len = items.length; i < len; i++) {

        if (items[i].properties.accessoryType == Ti.UI.LIST_ACCESSORY_TYPE_CHECKMARK) {

            api.UserSearch({

                method : facebook,

                id : items[i].properties.id

            }, function(success, res, code) {

                if (success == 1) {

                    users.push({

                        id : res.message._id,

                        creator : false

                    });

                } else {

                    // Its broke..

                }

            });

        } 

    }



    // WANT TO DO SOMETHING HERE with 'users' array once loop has finished 



}