我正在尝试将 DependencyService 与 Auth0 组件一起使用，但遇到了System.NullReferenceException: Object reference not set to an instance of an object 错误。
以下是我在 Android 项目中的代码：
namespace LoginPattern.Android
{
[assembly: Xamarin.Forms.Dependency (typeof(LoginPattern.Android.Auth0WidgetLogin))]
public class Auth0WidgetLogin : FormsApplicationActivity, LoginPattern.IAuth0WidgetLogin
{
private Auth0Client auth0 = new Auth0Client (
"xxx.auth0.com",
"xxxxxxxxxxxxxx");
public Auth0WidgetLogin ()
{
}
public async Task<LoginPattern.User> LoginUseAuth0EmbeddedWidget()
{
Auth0User usr = null;
try {
usr = await this.auth0.LoginAsync(Forms.Context);
} catch (Exception ex) {
throw ex;
}
LoginPattern.User userObj = new User(usr.Auth0AccessToken);
return userObj;
}
}
}
这在共享库中：
namespace LoginPattern
{
public interface IAuth0WidgetLogin
{
Task<User> LoginUseAuth0EmbeddedWidget();
}
public class User
{
public User(
string accessToken)
{
AccessToken = accessToken;
}
public string AccessToken {get; private set;}
public string Scope {get; private set;}
}
}
调用依赖服务时出现错误：
public async void Login ()
{
LoginPattern.User usr = null;
usr = await DependencyService.Get<IAuth0WidgetLogin>().LoginUseAuth0EmbeddedWidget();
App.Current.Properties["IsLoggedIn"] = true;
}