Ensuring correct date/time
<p>we are creating a location-enabled app where users use this app to record certain events in the field. </p>

<p>The important part of the event data is when an event happened. This is no issue when user is online, but we also support situations when user is offline (by remembering &amp; later syncing events). </p>

<p>There could be situations when users are offline and they change the time on the phone, so that event times are wrongly recorded.</p>

<p>So, what would be the best way to ensure we get a correct time, independent of user actions,  given that device could be offline. Some ideas:</p>

<ol>
<li>GPS time. Is it possible to acquire it?</li>
<li>Tracking system time changes made by user? </li>
<li>Any other idea?</li>
</ol>

<p>Note: time does need second accuracy, approximately minute accuracy would be ok.</p>

<p>Note2: we are creating mobile apps for Android and iPhone, so I'm interested for generic solutions and also solutions that are specific to any of those two platforms.</p>
