Initialising ' ... *__strong' with an expression of incompatible type 'id<UIApplicationDelegate> _Nullable'
<p>I have just updated my copy of Xcode and find that I now have lots of warnings. I am struggling to get the following one sorted out though:</p>

<pre><code>ObAppDelegate *appdelegate = [[UIApplication sharedApplication]delegate];
</code></pre>

<p>causes this warning:</p>

<blockquote>
  <p>Initializing <code>ObAppDelegate *__strong</code> with an expression of
  incompatible type <code>id&lt;UIApplicationDelegate&gt; _Nullable</code></p>
</blockquote>

<p>Can anyone point me in the right direction to fix this warning? For information this is the related code used prior to the problem line:</p>

<pre><code>- (NSManagedObjectContext *) managedObjectContext {
    return [(ObAppDelegate *) [[UIApplication sharedApplication] delegate] managedObjectContext];
}
</code></pre>