How to trigger dialogDidCancel message from FBPermissionDialog?

FBPermissionDialog is official Facebook iPhone lib. But my code to triggering message

- (void)dialogDidCancel开发者_如何学C:(FBDialog*)dialog

is not working. What can I do for this?

It was wrong place. The triggering method should be

/**
 * Called when a user closes the login dialog without logging in.
 */
- (void)sessionDidNotLogin:(FBSession*)session;

I hope this help.