Dismiss facebook window programmatically - ios

Question

My requirement is to close Facebook window in certain conditions via code.
I am using Facebook iOS SDK 3.5.1.
Is there any way to get visible (Facebook) screen on running app or to dismiss Facebook screen programmatically?
I am using facebook for 2 scenarios-
for login
for sending app request.
Code for both are below-
1. For login:
AppDelegate *appDelegate = (AppDelegate*)[UIApplication sharedApplication].delegate;
if (appDelegate.session.state != FBSessionStateCreated || !appDelegate.session.isOpen) {
// Create a new, logged out session.
NSArray *permissions = [NSArray arrayWithObjects:#"publish_stream",#"user_birthday",#"user_photos", #"email", #"user_location", #"user_hometown", nil];
appDelegate.session = [[FBSession alloc] initWithPermissions:permissions];
}
[appDelegate.session openWithCompletionHandler:^(FBSession *session,
FBSessionState status,
NSError *error) {
if (appDelegate.session.state!=258 && appDelegate.session.state!=257) {
[self accessTokenFound:appDelegate.session.accessToken];
}
}];
2. For app requests
NSMutableDictionary* params = [NSMutableDictionary dictionary];
AppDelegate* appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
[params setObject:friendID forKey:#"to"];
// Display the requests dialog
[FBWebDialogs
presentRequestsDialogModallyWithSession:appDelegate.session
message:message
title:nil
parameters:params
handler:^(FBWebDialogResult result, NSURL *resultURL, NSError *error) {
if (error) {
NSLog(#"Error sending request.");
} else {
if (result == FBWebDialogResultDialogNotCompleted) {
NSLog(#"User canceled request.");
} else {
NSDictionary *urlParams = [self parseURLParams:[resultURL query]];
if (![urlParams valueForKey:#"request"]) {
NSLog(#"User canceled request.");
} else {
NSString *requestID = [urlParams valueForKey:#"request"];
[self requestSentSuccessfully];
}
}
}
}];