Parse Facebook logInWithPermissions crash

I'm developing an iOS app with Parse, and implementing Twitter and Facebook login. My code is as follows;

var permissions = NSArray(array: ["user_about_me"])
    PFFacebookUtils.logInWithPermissions(permissions, {
    (user: PFUser!, error: NSError!) -> Void in
      if user == nil {
          NSLog("Uh oh. The user cancelled the Facebook login.")
      } else if user.isNew {
          //Get data and fill in appropriate fields for PFUser
      } else {
          //login user
      }
    })

The problem is that when I click the button that runs this code, I get an error with the following text:

Error: Error Domain=PF_AFNetworkingErrorDomain Code=-1016 "Expected content type {(
    "text/json",
    "application/json",
    "text/javascript"
)}, got text/html" UserInfo=0x79faa000 {NSLocalizedRecoverySuggestion=Invalid OAuth Request, PF_AFNetworkingOperationFailingURLResponseErrorKey=<NSHTTPURLResponse: 0x7a174da0> { URL: http://ift.tt/1wAF9pF } { status code: 200, headers {
    "Access-Control-Allow-Methods" = "*";
    "Access-Control-Allow-Origin" = "*";
    Connection = "keep-alive";
    "Content-Length" = 21;
    "Content-Type" = "text/html; charset=utf-8";
    Date = "Sat, 21 Feb 2015 20:12:11 GMT";
    Server = "nginx/1.6.0";
    "X-Parse-Platform" = G1;
    "X-Runtime" = "0.005746";
} }, NSErrorFailingURLKey=http://ift.tt/1wAF9pF, NSLocalizedDescription=Expected content type {(
    "text/json",
    "application/json",
    "text/javascript"
)}, got text/html, PF_AFNetworkingOperationFailingURLRequestErrorKey=<NSMutableURLRequest: 0x7a165300> { URL: http://ift.tt/1wAF9pF }} (Code: 100, Version: 1.6.0)
2015-02-21 14:12:11.851 hotPotato[90663:4004200] Uh oh. The user cancelled the Facebook login.

It appears that something about my "permissions" array is not correct. However, I think I've followed Parse's instructions exactly save the fact that I am translating into swift. Any ideas?