When I try to POST from RestKit, there is a warning in Rails console:

Started POST "/friends" for 127.0.0.1 at 2012-04-16 09:58:10 +0800
Processing by FriendsController#create as */*
Parameters: {"friend"=>{"myself_id"=>"m001", "friend_id"=>"f001"}}
WARNING: Can't verify CSRF token authenticity
(0.1ms)  BEGIN
SQL (1.7ms)  INSERT INTO `friends` (`friend_id`, `myself_id`) VALUES ('f001', 'm001')
(1.1ms)  COMMIT
Redirected to http://127.0.0.1:3000/friends/8
Completed 302 Found in 6ms (ActiveRecord: 3.0ms)

Here is client code:

NSMutableDictionary *attributes = [[NSMutableDictionary alloc] init];
[attributes setObject: @"f001" forKey: @"friend_id"];
[attributes setObject: @"m001" forKey: @"myself_id"];
NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObject:attributes forKey:@"friend"];
[[RKClient sharedClient] post:@"/friends" params:params delegate:self];

How can I get rid of the warning?

Edit
Report