Set NSUserDefault with timestamp from a timepicker
<p>I´m trying to get the value from a date picker, convert it to a timeStamp and then set a <code>NSUserDefaults</code> with the timestamp value. But I get multiple error messages.</p>
<blockquote>
<p>1: Implicit conversation of time_t (aka long) to id_Nullable is disallowed with ARC</p>
<p>2: incompatible integer to pointer conversation sending time_t (aka long) to parameter of type _id Nullable is disallowed with ARC</p>
</blockquote>
<pre><code>- (IBAction)createActivityButtonPressed:(id)sender {
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    time_t dateStart = (time_t) [self.datePicker.date timeIntervalSince1970];
    [defaults setObject:dateStart forKey:@&quot;TimeStartString&quot;];
}
</code></pre>