Exposed filter for data and select field
According to the docs here drupalgap.org/node/498 the filter should be added to your app when you create it in your view and then publish it. If those instructions do not work to create a simple filter, I suggest raising and issue over there.

As to Date filtering, I expect that only the select list exposed form items will transfer to your app out-of-the-box. If you want some custom UI elements such as jQuery mobile date picker to match the rest of your app UI, you will have to use a text field in the views exposed filter then edit the code on you app to call the UI element.

A lot of the time with similar things, I end up creating icon links in the header that act like filters and sorters e.g.

&lt;?php
print l("&lt;i class='icon icon-cancel-circled'&gt;&lt;/i&gt;", "my/view", array('html' =&gt; TRUE, 'query' =&gt; array('sort_by' =&gt; 'created', 'sort_order' =&gt; 'ASC')));
?&gt;


This makes an arrow up icon link (if you're implementing icons somehow) which will go to the view sorted by "created" "ascending".

Having an exposed filters form in an app is often too much for a small screen when a few icons will do, and this should transfer to your app in the header ok.