使用类方法时无法导航到页面

Question

我正在开发Windows Phone 8.1通用应用程序，其中我创建了一个类方法并将其放置在应用程序中其中一个页面的NavigationHelper_LoadState方法中。我的导航如下，我单击主页上的链接，这将我带到有问题的页面，我将类方法放置在 LoadState 中。

类方法检查用户的身份验证状态。如果用户没有登录，它应该将他带到一个单独的登录页面（SHDSignIn来自下面的代码片段）。

我

遇到的问题是，当我在类方法中点击那部分代码时，它只是逐步执行重定向代码，但不会将我带到登录页面，而是将我带到从主页单击的页面。

从我到目前为止所做的故障排除似乎是一个问题，可能是因为我从NavigationHelper_LoadState调用该方法并且系统不喜欢它？？有人可以解释一下并提供解决方法吗？

这是我的类函数代码：

public async void SHDAuthState(string errormessage, ProgressBar myprogressbar, TextBlock mytextblock, TextBlock myservernetworkerror)
{
    //Get the values for the userID and password from the settings....
    string shdLoggedInValue = (string)appRoamingSettings.Values["shdLoggedIn"];
    //If not logged in, redirect to the SHD sign in page...
    if (shdLoggedInValue != "Yes")
    {
        this.rootFrame.Navigate(typeof(SHDSignIn));
    }
    //Getting the cookie if it has expired..
    else
    {
        //Get the cookie value...
        string myCookieValue = (string)appRoamingSettings.Values["MyCookie"];
        //Get the original cookie obtain time....
        long CookieObtainedTimeValue = (long)appRoamingSettings.Values["CookieObtainedTime"];
        //Convertig date/time back to DateTime object....
        origCookieObtainedTime = DateTime.FromBinary(CookieObtainedTimeValue);
        currentDateTime = DateTime.Now;
        //Check to see if cookie has expired....
        cookieTimeElasped = currentDateTime - origCookieObtainedTime;
        cookieTimeElapsedMins = cookieTimeElasped.TotalMinutes;
        //  2 days = 2880 mins but we give a margin of 1 minute
        //Get a new cookie if it has expired and save to settings
        if (cookieTimeElapsedMins >= 2879)
        {
            // Start showing the progress bar...      
            mycontrols.progressbarShow(myprogressbar, mytextblock);
            //Get the values for the userID and password from the settings....
           string UserIDValue = (string)appRoamingSettings.Values["UserID"];
           string PasswordValue = (string)appRoamingSettings.Values["Password"];
           //Update the requestData string before sending.....
           requestData = "{" + string.Format(RegisterRequestData, UserIDValue, PasswordValue) + "}";
           string registerResults = await SHDAPI(registerUrl, requestData, errormessage);
           if (registerResults != null)
           {
                // Get the cookie and the time and save it to settings
                var shdCookie = JsonConvert.DeserializeObject<SHDHelper.SHDObject>(registerResults).RegistrationCookie;
                //Save cookie to the app settings
                appRoamingSettings.Values["MyCookie"] = shdCookie;
                //*************************************
                //  build the UI
                //*************************************
               // Stop showing the progress bar...      
               mycontrols.progressbarNoShow(myprogressbar, mytextblock);
           }
           else
           {
               // Stop showing the progress bar...
               mycontrols.progressbarNoShow(myprogressbar, mytextblock);
               //Show the error message...
               myservernetworkerror.Visibility = Windows.UI.Xaml.Visibility.Visible;
            }
        }
    }
}

另外，我在类中定义了如下根框架：

 Frame rootFrame = Window.Current.Content as Frame;

我从 LoadState 方法调用类方法，如下所示：

 SHD_helper.SHDAuthState(errorMessage, pgbar, pgText, ServerNetworkError);

谢谢！

Answer 1

我认为Navigate方法甚至在加载第一页之前就被调用了......

您是否尝试过将该方法放入新的调度程序操作中？

rootFrame.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
    delegate
    {
        rootFrame.Navigate(typeof (SHDSignIn));
    });

但我认为你不应该在 LoadState 回调中检查这一点......