title: Facebook ios sdk Graph request allows only one field as parameter
body: <p>I'm developing an app which requires facebook login, and user details. However, the same code that I used in previous apps for fb login doesn't work, and I need to make separate graph requests for each field like name, email, picture, etc.</p>
  
  <p>Basically, whenever I try to do the following:</p>
  
  <pre><code>connection.add(GraphRequest(graphPath: "/me", parameters:["fields":"email, name, picture"])) { httpResponse, result in
                  switch result {
                  case .success(let response):
                      guard let userInfo = response.dictionaryValue else {
                          return
                      }
                      userDict["email"] = userInfo["email"]! as Any
                      UserDefaults.standard.set(userDict["email"], forKey: userKeys.email)
                  case .failed(let error):
                      print("Graph Request Failed: \(error)")
                  }
              }
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>Graph Request Failed: Error Domain=com.facebook.sdk.core Code=8 "(null)" UserInfo={com.facebook.sdk:FBSDKGraphRequestErrorCategoryKey=0, com.facebook.sdk:FBSDKGraphRequestErrorHTTPStatusCodeKey=400, com.facebook.sdk:FBSDKErrorDeveloperMessageKey=Syntax error "Expected end of string instead of "%"." at character 5: email%2C%20name%2C%20picture, com.facebook.sdk:FBSDKGraphRequestErrorGraphErrorCode=2500, com.facebook.sdk:FBSDKGraphRequestErrorParsedJSONResponseKey={
  body =     {
      error =         {
          code = 2500;
          "fbtrace_id" = "FIc1yiUL+1z";
          message = "Syntax error \"Expected end of string instead of \"%\".\" at character 5: email%2C%20name%2C%20picture";
          type = OAuthException;
      };
  };
  code = 400;
  </code></pre>
  
  <p>And a similar error when I do:</p>
  
  <pre><code>connection.add(GraphRequest(graphPath: "/me", parameters:["fields":"picture.type(large)"]))
  </code></pre>
  
  <p>However, it doesn't give an error when I put in a single field as a parameter.</p>
  
  <p>Any help would be greatly appreciated :)</p>