Can't add user to existing Parse.com role

Question

With this code, I try to add user to existing Parse.com role "banned":

 var roleACL = PFACL()
 var role = PFRole(name: "banned", acl:roleACL)
 role.users.addObject(userObject) // This should add user
 role.saveInBackground()

I get error 137 A duplicate value for a field with unique values was provided (Code: 137, Version: 1.6.1)

I guess it tries to recreate the role. However, form the doc, at https://www.parse.com/docs/ios_guide#roles-security/iOS I don't see how i can add a user to an existing role.

Answer 1

Got the solution. The misleading code above, as is on Parse.com site tries to recreate a role. The correct code is :

var queryRole = PFRole.query() // You need to get role object
queryRole.whereKey("name", equalTo:"banned")
queryRole.getFirstObjectInBackgroundWithBlock() {
(roleObject: PFObject!, error: NSError!) -> Void in
if error == nil {

      // Assign user to banned role
      var roleToAddUser = roleObject as PFRole
      roleToAddUser.users.addObject(userObject)
      roleToAddUser.saveInBackground()

     }
}