title: UIImageView setImage crashes on background thread since Xcode 10
body: <p>Since Xcode 10 on iOS, the following is crashing with:
  <code>[Animation] +[UIView setAnimationsEnabled:] being called from a background thread. Performing any operation from a background thread on UIView or a subclass is not supported and may result in unexpected and insidious behavior. trace=...</code></p>
  
  <p>when launched from background thread.</p>
  
  <pre><code>+(UIImage *)circularImage:(UIImage *)image withDiameter:(NSUInteger)diameter
  {
      CGRect frame = CGRectMake(0.0f, 0.0f, diameter, diameter);
      UIImageView *imageView = [[UIImageView alloc] initWithFrame:frame];
      imageView.contentMode = UIViewContentModeScaleAspectFill;
      imageView.clipsToBounds = YES;
      [imageView setImage:image]; &lt;--- crashing here
  ...
  }
  </code></pre>
  
  <p>Is that normal that I can't assign a simple UIImage to an UIImageView in a background thread ?</p>