title: Add an image for UIActivityindicator in Objective-C
body: <p>I used this code in viewDidLoad,but the image is not shown before loading the image.</p>
  
  <pre><code>NSString *ImageString=@"http://images.all-free-download.com/images/graphiclarge/daisy_pollen_flower_220533.jpg";
  
  UIImage *HeartImage=[UIImage imageNamed:@"Heart.png"];
  
  UIImageView *HeartImageView=[[UIImageView alloc]initWithImage:HeartImage];
  
  activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
  activityIndicator.center=self.WebimageView.center;
  activityIndicator.frame = CGRectMake(15, 15, 30, 30);
  activityIndicator.hidesWhenStopped = YES;
  activityIndicator.hidden = NO;
  [activityIndicator startAnimating];
  activityIndicator.center = CGPointMake(self.WebimageView.frame.size.width /2, self.WebimageView.frame.size.height/2);
  // [HeartImageView addSubview:activityIndicator];
  [self.WebimageView sd_setImageWithURL:[NSURL URLWithString:ImageString]
                       placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
  
  
  [self.WebimageView addSubview:activityIndicator];
  </code></pre>