title: App converted to ARC, now getting warnings about my properties
body: <p>I just converted my app to <code>ARC</code>, and while it builds fine, I get like 600 warnings, all pertaining to my properties.  Such as:</p>
  
  <blockquote>
    <p>Default property attribute 'assign' not appropriate for non-gc object</p>
    
    <p>No 'assign', 'retain' or 'copy' attribute is specified - 'assign' is
    assumed</p>
  </blockquote>
  
  <p><a href="https://i.stack.imgur.com/TzJMa.png" rel="noreferrer"><img src="https://i.stack.imgur.com/TzJMa.png" alt="Screenshot for warning"></a></p>
  
  <p>After Xcode converted my code, here is what my properties look like:</p>
  
  <pre><code>@property (nonatomic) EKEventStore *eventStore;
  @property (nonatomic) EKCalendar *defaultCalendar;
  @property (nonatomic) UIActionSheet *currentActionSheet;
  @property (nonatomic) UILabel *noEventLabel;
  </code></pre>
  
  <p>Someone talked about needing to add <code>strong</code> to all of these.  Is this the case?  Did Xcode forget to add something?</p>