What browser are you using? There has been some issues opening application in the latest version of chrome. I would also make sure you are on latest iOS version (8.3).
Are you opening it on the same network? Or 3G/4G? Sense needs to establish a Websocket connection so if there is anything interrupting that (proxy for example) there could be issues.
I faced the same issue as well. Its a simple fix.
In the management console, under the proxy settings , check the "enable http". Doing this you will be able to access Qliksense through http://xxx and doing which the http port will be open.
This will allow you to view the dashboards on ios devices as well
Hope this helps
- Sangram Reddy.