Getting publish_stream extended permission from the user

I was ussing Facbook connect in my iPhone app, but in december the posts stopped working. After some research I found that i'm supossed to use stream.publish, something like:

NSString *att = @"{\"bob\":\"i\'m happy\",\"caption\": \"User rated the internet 5 stars\", \"description\": \"a giant cat\"}";
    NSDictionary *attachment = [NSDictionary dictionary开发者_StackOverflowWithObject:att forKey:@"attachment"];
    [[FBRequest requestWithDelegate:self] call:@"facebook.stream.publish" params:attachment];

Which i think it's correct, but the posts still don't work. Someone told me that i need to get publish_stream extended permission from the user, but i dont know how to do that.

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Present the FBPermission dialog and ask the user for the extended permission

FBPermissionDialog* dialog = [[[FBPermissionDialog alloc] initWithSession:session] autorelease];
dialog.delegate = self;
dialog.permission = @"publish_stream";
[dialog show];