Matthew Pans's questions

我已经为 collectionview 添加了命令SelectionChangedCommand。SelectedItem

<CollectionView
        Margin="0,10,0,0"
        BackgroundColor="Transparent"
        IsVisible="{Binding Visibility}"
        ItemsSource="{Binding ImageItems}"
        ItemsLayout="VerticalGrid, 2"
        SelectionMode="Single"
        SelectionChangedCommand="{Binding ImageItemTappedCommand}"
        SelectedItem="{Binding LastImageTappedItem, Mode=TwoWay}"
        HeightRequest="{Binding ImageHeight}">
    <CollectionView.ItemTemplate>
        <DataTemplate>
            <StackLayout BackgroundColor="{Binding ImageBGColor}">

ImageItemTapped命令：

public NameMatchViewModel() {
    ImageItemTappedCommand = new Command((obj) = >{
        try {
            //reset the bg color 
            foreach(var item in ImageItems) {
                item.ImageBGColor = Colors.White;
            }
            NameMatchList imageList = obj as NameMatchList;
            if (imageList != null) {
                Debug.WriteLine("**not null**");
            }
            else {
                Debug.WriteLine("**null**");
            }
            int index = ImageItems.IndexOf(imageList);
            imageList.ImageBGColor = Color.FromArgb("#0091da");
            //Storing name and imageurl to local db
            if (Utility.IsInternet()) {
                Preferences.Default.Set("NameMatchImageList_Image", imageList.imageUrl);
            }
            else {
                Preferences.Default.Set("NameMatchImageList_Image", imageList.FullImageUrl);
            }
            Preferences.Default.Set("NameMatchImageList_Name", imageList.name);
            Preferences.Default.Set("ImageItem", imageList);
            isImageSelected = true;
            if (isImageSelected && isNameSelected) {
                //If both image and name selected by player startes checking the matching
                StartNameMatchCheck(imageList);
            }
        }
        catch(Exception imagetapEx) {
            Debug.WriteLine("imagetapEx:>>" + imagetapEx);
        }
    });
}

但是当我尝试获取 selecteditem 值时，我得到的是 null。对于上述代码，我得到以下异常：

以下行除外：

imageList.ImageBGColor = Color.FromArgb("#0091da");

**null**
12:30:36:070    [0:] imagetapEx:>>System.NullReferenceException: Object reference not set to an instance of an object.
12:30:36:070       at MyProjectName.Model.NameMatchViewModel.<.ctor>b__98_0(Object obj) in E:\My Projects\MAUI\MyProjectName-app-maui\MyProjectName\Model\NameMatchViewModel.cs:line 390

我如何获取选定项目的值？

我Plugin.InAppBilling在我的 MAUI 应用程序中使用它进行订阅。对于 Android 部分，我需要在成功购买后进行确认。

选项 1：ConsumePurchaseAsync

if (DeviceInfo.Platform == DevicePlatform.Android)
{
    var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(productId, purchase.PurchaseToken);
    if (!consumed)
    {
        Debug.WriteLine("Purchase consumption/acknowledgment failed");
        return;
    }
    Debug.WriteLine("Purchase acknowledged successfully");
}

但我遇到了以下异常：

16:05:10:848    [0:] purchaseEx:>>Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase.
16:05:10:848       at Plugin.InAppBilling.InAppBillingImplementation.ParseBillingResult(BillingResult result, Boolean ignoreInvalidProducts)
16:05:10:848       at Plugin.InAppBilling.InAppBillingImplementation.ConsumePurchaseAsync(String productId, String transactionIdentifier)
16:05:10:848       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
16:05:10:848    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 371
16:05:10:909    The thread 25 has exited with code 0 (0x0).

以下行存在异常：

var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(productId, purchase.PurchaseToken);

选项 2：DependencyService

创建了一个接口：IPurchaseAcknowledgment

public interface IPurchaseAcknowledgment
{
    Task<bool> AcknowledgePurchaseAsync(string purchaseToken);
}

实施IPurchaseAcknowledgment日期MainActivity：

public class MainActivity : MauiAppCompatActivity, IPurchaseAcknowledgment
{
    /// <summary>
    /// Acknowledge purchase using Google Play BillingClient
    /// </summary>
    public async Task<bool> AcknowledgePurchaseAsync(string purchaseToken)
    {
        var billingClient = BillingClient.NewBuilder(Android.App.Application.Context)
            .SetListener(new PurchaseUpdateListener()) // You can implement your own listener if needed
            .EnablePendingPurchases()
            .Build();

        // Connect to the BillingClient
        var billingConnectionTaskCompletionSource = new TaskCompletionSource<BillingResult>();
        billingClient.StartConnection(new BillingClientStateListener(
            onBillingSetupFinished: billingResult => billingConnectionTaskCompletionSource.SetResult(billingResult),
            onBillingServiceDisconnected: () => billingConnectionTaskCompletionSource.SetException(new System.Exception("Billing service disconnected"))
        ));

        var connectionResult = await billingConnectionTaskCompletionSource.Task;
        if (connectionResult.ResponseCode != BillingResponseCode.Ok)
        {
            return false; // Connection failed
        }

        // Acknowledge the purchase
        var acknowledgeParams = AcknowledgePurchaseParams.NewBuilder()
            .SetPurchaseToken(purchaseToken)
            .Build();

        var acknowledgeTaskCompletionSource = new TaskCompletionSource<BillingResult>();
        billingClient.AcknowledgePurchase(acknowledgeParams, new AcknowledgePurchaseResponseListener(
            result => acknowledgeTaskCompletionSource.SetResult(result)
        ));

        var acknowledgeResult = await acknowledgeTaskCompletionSource.Task;

        // End connection
        billingClient.EndConnection();

        return acknowledgeResult.ResponseCode == BillingResponseCode.Ok;
    }

    /// <summary>
    /// Listener for purchase updates (can be extended if required)
    /// </summary>
    private class PurchaseUpdateListener : Java.Lang.Object, IPurchasesUpdatedListener
    {
        public void OnPurchasesUpdated(BillingResult billingResult, IList<Purchase> purchases)
        {
            // Handle purchase updates here if needed
        }
    }

    /// <summary>
    /// Listener for billing client state
    /// </summary>
    private class BillingClientStateListener : Java.Lang.Object, IBillingClientStateListener
    {
        private readonly System.Action<BillingResult> onBillingSetupFinished;
        private readonly System.Action onBillingServiceDisconnected;

        public BillingClientStateListener(System.Action<BillingResult> onBillingSetupFinished, System.Action onBillingServiceDisconnected)
        {
            this.onBillingSetupFinished = onBillingSetupFinished;
            this.onBillingServiceDisconnected = onBillingServiceDisconnected;
        }

        public void OnBillingSetupFinished(BillingResult billingResult)
        {
            onBillingSetupFinished?.Invoke(billingResult);
        }

        public void OnBillingServiceDisconnected()
        {
            onBillingServiceDisconnected?.Invoke();
        }
    }

    /// <summary>
    /// Listener for acknowledge purchase response
    /// </summary>
    private class AcknowledgePurchaseResponseListener : Java.Lang.Object, IAcknowledgePurchaseResponseListener
    {
        private readonly System.Action<BillingResult> onAcknowledgeResponse;

        public AcknowledgePurchaseResponseListener(System.Action<BillingResult> onAcknowledgeResponse)
        {
            this.onAcknowledgeResponse = onAcknowledgeResponse;
        }

        public void OnAcknowledgePurchaseResponse(BillingResult billingResult)
        {
            onAcknowledgeResponse?.Invoke(billingResult);
        }
    }
}

购买计划后最终结果：

if (DeviceInfo.Platform == DevicePlatform.Android)
{
    var acknowledgmentService = DependencyService.Get<IPurchaseAcknowledgment>();
    var acknowledged = await acknowledgmentService.AcknowledgePurchaseAsync(purchase.PurchaseToken);

    if (!acknowledged)
    {
        Debug.WriteLine("Purchase acknowledgment failed");
        return;
    }
    Debug.WriteLine("Purchase acknowledged successfully");
}

但出现以下异常：

16:23:24:835    [0:] exception:>>System.NullReferenceException: Object reference not set to an instance of an object.
16:23:24:835       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
16:23:24:835    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 383

以下行存在异常：

var acknowledged = await acknowledgmentService.AcknowledgePurchaseAsync(purchase.PurchaseToken);

还有其他解决办法吗？

更新

我尝试如下：

var consumed = await CrossInAppBilling.Current.ConsumePurchaseAsync(purchase.ProductId, purchase.TransactionIdentifier);

但出现以下异常：

12:43:02:766    [0:] purchaseEx:>>Plugin.InAppBilling.InAppBillingPurchaseException: Unable to process purchase.
12:43:02:766       at Plugin.InAppBilling.InAppBillingImplementation.ParseBillingResult(BillingResult result, Boolean ignoreInvalidProducts)
12:43:02:766       at Plugin.InAppBilling.InAppBillingImplementation.ConsumePurchaseAsync(String productId, String transactionIdentifier)
12:43:02:766       at MyProjectName.Pages.ListPlansPage.PlanClicked(Object sender, EventArgs e) in E:\My Projects\MAUI
12:43:02:766    eedhelp-app-maui\MyProjectName\Pages\Subscription\ListPlansPage.xaml.cs:line 372

我正在尝试在发布模式下打印调试器语句来解决一个问题。

为此我做了以下改变：

1 在.csproj 文件上添加了 DebugType、DebugSymbols、Debuggable 和 AndroidEnableDeveloperInstrumentation。

<PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|net8.0-android|AnyCPU'">
  <ApplicationId>com.companyname.appname</ApplicationId>
  <AndroidPackageFormat>apk</AndroidPackageFormat>
  <ApplicationTitle>appname</ApplicationTitle>
  <DebugType>portable</DebugType>
  <DebugSymbols>true</DebugSymbols>
  <Debuggable>true</Debuggable>
  <AndroidEnableDeveloperInstrumentation>true</AndroidEnableDeveloperInstrumentation>
</PropertyGroup>

2 在应用程序下的android manifext文件中添加android:debuggable="true"。

3 在MAUIProgram.cs中添加以下代码。

builder.Logging.AddConsole(options =>
{
    options.IncludeScopes = true;
});
builder.Logging.SetMinimumLevel(LogLevel.Debug);

4. 在 App.xaml.cs 下添加以下代码。

   使用 Microsoft.Extensions.Logging；

   公共部分类 App:应用程序 { 公共 App(ILogger logger) { InitializeComponent();

        logger.LogInformation("App started in production mode.");
        logger.LogError("An error occurred.");
    }
   

   }

5. 在项目属性下启用开发人员工具以进行发布模式。

但是当我在发布模式下运行时，我看到的是以下屏幕。

在发布模式下查看调试器语句还有其他变化吗？

同时点击电源按钮和音量按钮时是否可以在移动应用程序上触发事件？

当用户在移动设备上触发任意密钥组合时，我需要在用户界面上显示一个秘密选项（标签）。

有什么选择吗？我只提到电源按钮+音量按钮，如果有其他组合可用，请建议？

将目标 Android 版本升级到 12 后，我无法部署我的应用程序，并收到以下错误：

错误ADB0010：Mono.AndroidTools.InstallFailedException：意外的安装输出：失败[INSTALL_PARSE_FAILED_MANIFEST_MALFORMED：installPackageLI期间解析失败：/data/app/vmdl1678539237.tmp/base.apk（位于二进制XML文件第23行）：crc64045f0433dcf30634.FirebaseNotificationService：目标荷兰国际集团S+ （版本 31 及更高版本）要求在存在意图过滤器时定义 android:exported 的显式值]

这是我的 Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="testapp.com" android:installLocation="preferExternal" android:versionCode="31" android:versionName="4.1">
    <uses-sdk android:minSdkVersion="15" android:targetSdkVersion="31" />
    <application android:label="Test App" android:icon="@drawable/icon" android:usesCleartextTraffic="true" android:allowBackup="false">
        <receiver android:name="com.google.firebase.iid.FirebaseInstanceIdInternalReceiver" android:exported="false" />
        <receiver android:name="com.google.firebase.iid.FirebaseInstanceIdReceiver" android:exported="true" android:permission="com.google.android.c2dm.permission.SEND">
            <intent-filter>
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
                <category android:name="${applicationId}" />
            </intent-filter>
        </receiver>
    </application>
</manifest>

我该如何解决这个问题？请提出一个解决方案。