How to sign out with Google+ on iPhone

I am writing an application where user can login using Google+. I followed GOOGLE Developer console and successfully logged in and obtained the user profile information through Access_Token. and i want to login through web view, but how to make sign out after login?

My Webview method

-(void)addWebView
{

    NSString *url = [NSString stringWithFormat:@"http://ift.tt/Kyk9ty",client_id,callbakc,scope,visibleactions];

    self.webview = [[UIWebView alloc]init];
    self.webview.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
    self.webview.delegate = self;
    [self.view addSubview:self.webview];
    [self.webview  loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]]];


}
- (BOOL)webView:(UIWebView*)webView shouldStartLoadWithRequest:(NSURLRequest*)request navigationType:(UIWebViewNavigationType)navigationType {
    //    [indicator startAnimating];
    if ([[[request URL] host] isEqualToString:@"localhost"]) {

        // Extract oauth_verifier from URL query
        NSString* verifier = nil;
        NSArray* urlParams = [[[request URL] query] componentsSeparatedByString:@"&"];
        for (NSString* param in urlParams) {
            NSArray* keyValue = [param componentsSeparatedByString:@"="];
            NSString* key = [keyValue objectAtIndex:0];
            if ([key isEqualToString:@"code"]) {
                verifier = [keyValue objectAtIndex:1];
                NSLog(@"verifier %@",verifier);
                break;
            }
        }

        if (verifier) {
            NSString *data = [NSString stringWithFormat:@"code=%@&client_id=%@&client_secret=%@&redirect_uri=%@&grant_type=authorization_code", verifier,client_id,secret,callbakc];
            NSString *url = [NSString stringWithFormat:@"http://ift.tt/IlrJjr"];
            NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:url]];
            [request setHTTPMethod:@"POST"];
            [request setHTTPBody:[data dataUsingEncoding:NSUTF8StringEncoding]];
            NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:request delegate:self];
            receivedData = [[NSMutableData alloc] init];

        } else {
            // ERROR!
        }

        [webView removeFromSuperview];

        return NO;
    }
    return YES;
}

via Chebli Mohamed