iOS：Google身份验证代码

我正在使用身份验证用户来使用与之关联的Google帐户.问题是,每次用户通过我的应用程序登录时,“允许访问”始终显示在Google的身份验证视图中,即使我已经从先前的测试中单击了“允许访问”.这是正常的还是我的代码错了？请帮帮我们.

我在out中使用以下代码进行登录：

- (IBAction)signIn:(id)sender {
    if(!isSignedIn){
        [self signOutFromAll];

        Nsstring *keychainItemName = nil;

        // save keychain
        keychainItemName = kKeychainItemName;

        Nsstring *scope = @"https://www.googleapis.com/auth/plus.me";

        Nsstring *clientID = kClientID;
        Nsstring *clientSecret = kClientSecret;

        SEL finishedSel = @selector(viewController:finishedWithAuth:error:);

        GTMOAuth2ViewControllerTouch *viewController;
        viewController = [GTMOAuth2ViewControllerTouch controllerWithScope:scope 
                                                                  clientID:clientID 
                                                              clientSecret:clientSecret 
                                                          keychainItemName:keychainItemName 
                                                                  delegate:self 
                                                          finishedSelector:finishedSel];

        [[self navigationController]pushViewController:viewController animated:YES]; 
    } else {
        [self displayAlertWithMessage:@"Currently Signed in."];
    } }

- (IBAction)signOut:(id)sender {
    [self signOutFromAll];
    [self displayAlertWithMessage:@"Signed out."]; }

这是代表：

- (void)viewController:(GTMOAuth2ViewControllerTouch *)viewController 
      finishedWithAuth:(GTMOAuth2Authentication *)auth 
                 error:(NSError *)error{
    if(error != nil){
        // Authentication Failed...
        NSLog(@"Authentication error: %@",error);
        NSData *responseData = [[error userInfo] objectForKey:@"data"];
        if([responseData length] > 0)
            NSLog(@"%@",[[[Nsstring alloc]initWithData:responseData encoding:NSUTF8StringEncoding]autorelease]);
        self.auth = nil;
    } else {
        // Authentication succeeded...
        isSignedIn = YES;
        self.auth = auth;
    }
}

和awakeFromNib：

- (void)awakeFromNib{
    // Fill in the Client ID and Client Secret text fields
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    // First,we'll try to get the saved Google authentication,if any,from the keychain
    // normal applications will hardcode in their client ID and client secret,// But the sample app allows the user to enter them in a text field,and saves them in the preferences
    Nsstring *clientID      = [defaults stringForKey:kGoogleClientIDKey];
    Nsstring *clientSecret  = [defaults stringForKey:kGoogleClientSecretKey];

    GTMOAuth2Authentication *auth;

    auth = [GTMOAuth2ViewControllerTouch authForGoogleFromKeychainForName:kKeychainItemName
                                                                 clientID:clientID
                                                             clientSecret:clientSecret];

    if (auth.canAuthorize) {
        // There is saved google authentication
        // self.serviceSegments.selectedSegmentIndex = 0;
    } 

    // Save the authentication object,which holds the auth tokens
    self.auth = auth;

    [self setAuth:auth];
    isSignedIn = self.auth.canAuthorize;
}

顺便说一句,我对这些代码的引用是在这个链接上：http://code.google.com/p/gtm-oauth2/wiki/Introduction#Using_the_OAuth_2_Controllers