Server requires signed URL (Unity Ads API)
<p>I want to fetch my statistics for Unity Ads in an iOS application. Unity provides an API for this, however they state that </p>

<blockquote>
  <p>"The statistics server always requires signed URLs and will not work
  if accessed without a valid signature."</p>
</blockquote>

<p>What is a signed URL and how should I access the server? A normal NSURLRequest does not work and I get the error message:
<code>{"error":"Authentication error","responseCode":500,"status":"error"}</code></p>

<p>Here is the code I am using(making a request this way works for other apis, just not with unity ads)</p>

<pre><code>- (IBAction)Button:(id)sender {
    // Create the request.
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://gameads-admin.applifier.com/stats/acquisition-api?apikey=979c4e733ccd85a1eaef74e28f9dc1742d5fa5a2b3518fe10825aa13caf18185"]];

    // Create url connection and fire request
    NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
}
</code></pre>