title: Why NSURLConnection is slower than stringWithContentsOfURL?
body: <p>I have a simple json file on <a href="http://img.soulapp.cn/appips.json" rel="nofollow noreferrer">http://img.soulapp.cn/appips.json</a>. I test it on Postman, the time is about 200ms.</p>
  
  <p>I tried </p>
  
  <pre><code>NSLog(@"%f",[[NSDate date] timeIntervalSince1970]);
  NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://img.soulapp.cn/appips.json"]];
  [NSURLConnection sendAsynchronousRequest:req queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
         NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
         NSLog(@"%f",[[NSDate date] timeIntervalSince1970]);
   }];
  </code></pre>
  
  <p>time is 4s.</p>
  
  <p>I tried </p>
  
  <pre><code>[NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://img.soulapp.cn/appips.json"] encoding:NSUTF8StringEncoding error:nil]
  </code></pre>
  
  <p>time is 200ms.</p>
  
  <p>Why <code>NSURLConnection</code> is slower than <code>stringWithContentsOfURL</code>?</p>
  
  <p>How to improve it or can i make <code>stringWithContentsOfURL</code> safer because it's synchronize method?</p>