我正在尝试从Android通知加载Xamarin表单页面。我真的迷失在这方面的机器人方面，我的大部分代码都是从教程和博客文章中拼凑而成的。但是，似乎没有什么能真正涵盖这种情况。
我已经使用依赖服务实现了一个非常简单的接口，以创建具有intent ...的通知。
[assembly: Xamarin.Forms.Dependency(typeof(QuoteNotification))]
namespace QuoteApp.Droid
{
class QuoteNotification : IQuoteNotification
{
public void Notify(string title, string message)
{
//type needs to be derived from java, not xamarin.forms
Intent LoadPostPage = new Intent(Forms.Context, typeof(DroidToForms));
const int pendingIntentId = 0;
PendingIntent pendingIntent =
PendingIntent.GetActivity(Forms.Context, pendingIntentId, LoadPostPage, PendingIntentFlags.OneShot);
Notification.Builder builder = new Notification.Builder(Forms.Context)
.SetContentIntent(pendingIntent)
.SetAutoCancel(true)
.SetContentTitle(title)
.SetContentText(message)
.SetSmallIcon(Resource.Drawable.icon);
// Build the notification:
Notification notification = builder.Build();
// Get the notification manager:
NotificationManager notificationManager =
Forms.Context.GetSystemService(Context.NotificationService) as NotificationManager;
// Publish the notification:
const int notificationId = 0;
notificationManager.Notify(notificationId, notification);
}
}
}
这称为活动 -
namespace QuoteApp.Droid
{
[Activity(Label = "QuoteApp", MainLauncher = true)]
class DroidToForms : Activity
{
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
StartActivity(typeof(XFPostPage));
//Xamarin.Forms.Application.Current.MainPage.Navigation.PushAsync(new QuoteApp.PostPage());
}
}
}
反过来调用这个表单页面，这里的所有代码都在Xamarin.Android项目中
namespace QuoteApp.Droid
{
/// <summary>
/// This is a Xamarin.Forms screen. It MUST:
/// * inherit from ANdroidActivity
/// * call Forms.Init()
/// * use LoadApplication()
/// </summary>
[Activity(Label = "XFPostPage", MainLauncher = true) ]
public class XFPostPage : Xamarin.Forms.Platform.Android.FormsApplicationActivity
{
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
Xamarin.Forms.Forms.Init(this, bundle);
//LoadApplication( new App() ); //how do i send to PostPage.xaml ??
Xamarin.Forms.Application.Current.MainPage.Navigation.PushAsync(new QuoteApp.PostPage());
}
}
}
这在logcat中给出了以下错误
07-04 17:51:44.494 7668 7668 E AndroidRuntime: Caused by: android.runtime.JavaProxyThrowable: System.NullReferenceException: Object reference not set to an instance of an object
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at QuoteApp.Droid.XFPostPage.OnCreate (Android.OS.Bundle bundle) [0x00016] in <ab64801c0fb24acb8457c1d1202cc143>:0
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x0000f] in <d855bac285f44dda8a0d8510b679b1e2>:0
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at (wrapper dynamic-method) System.Object:2780fa42-5931-40d3-8d14-a642f1a3025c (intptr,intptr,intptr)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at md543d03747be5a5b03a21a2a23b8ba191a.XFPostPage.n_onCreate(Native Method)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at md543d03747be5a5b03a21a2a23b8ba191a.XFPostPage.onCreate(XFPostPage.java:29)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.Activity.performCreate(Activity.java:6237)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.ActivityThread.-wrap11(ActivityThread.java)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.os.Looper.loop(Looper.java:148)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5417)
07-04 17:51:44.494 7668 7668 E AndroidRuntime: ... 3 more
我尝试了许多不同的想法都有不同的运行时错误，我对Xamarin.Android工作的理解非常有限。最终我将使用AlarmManager的通知，更多信息将发送到PostPage.Xaml。目前我只是迷失在这个错误的地方虽然？！
任何帮助将非常感谢，提前感谢。
答案 0 :(得分：2)
对于任何偶然发现此问题的人，我最终在OnNewIntent中使用了MainActivity。
这里有一些很好的信息Processing notifications in Xamarin Forms Android
我的代码最终看起来像这样。
调用依赖服务来获取android implmentation
DependencyService.Get<IQuoteNotification>().Notify("words",SelectedQuote.FixedTitle , SelectedQuote.Id);
使用Intent构建通知：
class QuoteNotification : IQuoteNotification
{
public void Notify(string title, string message, int postIndex)
{
//type needs to be derived from java, not xamarin.forms
Intent LoadPostPage = new Intent(Forms.Context, typeof(MainActivity));
LoadPostPage.PutExtra("NotificationTrue", true);
LoadPostPage.PutExtra("PostID", postIndex);
const int pendingIntentId = 0;
PendingIntent pendingIntent =
PendingIntent.GetActivity(Forms.Context, pendingIntentId, LoadPostPage, PendingIntentFlags.OneShot);
Notification.Builder builder = new Notification.Builder(Forms.Context)
.SetContentIntent(pendingIntent)
.SetAutoCancel(true)
.SetContentTitle(title)
.SetContentText(message)
.SetSmallIcon(Resource.Drawable.icon);
// Build the notification:
Notification notification = builder.Build();
// Get the notification manager:
NotificationManager notificationManager =
Forms.Context.GetSystemService(Context.NotificationService) as NotificationManager;
// Publish the notification:
const int notificationId = 0;
notificationManager.Notify(notificationId, notification);
}
}
然后在OnNewIntent中覆盖MainActivity。如果意图不是由我的QuoteNotification类构建，则发送-1作为PostID
protected override void OnNewIntent(Intent intent)
{
if (intent.HasExtra("NotificationTrue")){
LoadApplication(new App(intent.GetIntExtra("PostID", -1)));
//Xamarin.Forms.Application.Current.MainPage.Navigation.PushAsync(new QuoteApp.PostPage());
}
base.OnNewIntent(intent);
}
然后在App.Xaml.cs中添加一些逻辑以导航到正确的页面
public partial class App : Application
{
public App(int PostId = -1)
{
InitializeComponent();
if (PostId >= 0)
{
MainPage = new NavigationPage(new PostPage(PostId));
}
else
MainPage = new NavigationPage(new MainPage());
谢谢，希望它有所帮助。
答案 1 :(得分：1)
问题在于您的代码Intent LoadPostPage = new Intent(Forms.Context, typeof(DroidToForms));。
对于XF项目的Android平台，它只有一个Activity，即MainActivity，或者基于此MainActivity呈现XF页面。
所以你可以改变你这样的代码：
Intent intent = new Intent(context, typeof(MainActivity));
intent.PutExtras(valuesForActivity);
PendingIntent resultPendingIntent = PendingIntent.GetActivity(Xamarin.Forms.Forms.Context, 0, intent, PendingIntentFlags.OneShot);
然后使用OnCreate MainActivity方法：
//navigate to the page of PCL
Xamarin.Forms.Application.Current.MainPage.Navigation.PushAsync(new PostPage());
最后，正如@Pratik建议的那样，如果您要为Android平台创建原生页面/视图，请使用PageRenderer或ViewRenderer来执行此操作。