Xamarin.Forms - KeyNotFoundException: 字典中不存在给定的键 C#

Question

I am using Xamarin.Forms and I getting this error:

KeyNotFoundException: The given key was not present in the dictionary

For this line:

bool isLogin = (bool)Application.Current.Properties["isLogin"];

I tried to check to see if the key existed like so:

if(Application.Current.Properties.ContainsKey("isLogin"))
            {
                bool isLogin = (bool)Application.Current.Properties["isLogin"];

                string username = Application.Current.Properties["username"].ToString();

                if (isLogin)
                {
                    Application.Current.MainPage.Navigation.PushAsync(new MenuPage(), true);
                }
            }

But checking the key always returns false even after setting the key and value:

Application.Current.Properties["isLogin"] = true;

Answer 1

Application.Current.Properties will be exists even if you kill the application and restart it again. Just try in this way unplug your device and try to login and check, it will work. While debugging it won't work.