我的 MAUI 应用程序在 iOS 模拟器上的调试模式下运行良好，但是当我在 iPad 上以发布模式运行它时，在打开某个屏幕时出现以下神秘错误：
System.Reflection.TargetInvocationException: Arg_TargetInvocationException
---> System.InvalidProgramException
at Microsoft.Maui.Controls.Internals.TypedBinding`2[[OIL.ISA.ViewModels.SettingsViewModel, OIL.ISA, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].ApplyCore(Object sourceObject, BindableObject target, BindableProperty property, Boolean fromTarget)
at Microsoft.Maui.Controls.Internals.TypedBinding`2[[OIL.ISA.ViewModels.SettingsViewModel, OIL.ISA, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].Apply(Object context, BindableObject bindObj, BindableProperty targetProperty, Boolean fromBindingContextChanged)
at Microsoft.Maui.Controls.BindableObject.ApplyBindings(Boolean skipBindingContext, Boolean fromBindingContextChanged)
at Microsoft.Maui.Controls.BindableObject.SetInheritedBindingContext(BindableObject bindable, Object value)
at Microsoft.Maui.Controls.Element.SetChildInheritedBindingContext(Element child, Object context)
at Microsoft.Maui.Controls.Element.<OnBindingContextChanged>b__82_0(BindableObject child, Object bc)
at Microsoft.Maui.Controls.BindableObjectExtensions.PropagateBindingContext[Element](BindableObject self, IEnumerable`1 children, Action`2 setChildBindingContext)
at Microsoft.Maui.Controls.Element.OnBindingContextChanged()
at Microsoft.Maui.Controls.VisualElement.OnBindingContextChanged()
at Microsoft.Maui.Controls.View.OnBindingContextChanged()
at Microsoft.Maui.Controls.BindableObject.SetInheritedBindingContext(BindableObject bindable, Object value)
at Microsoft.Maui.Controls.Element.SetChildInheritedBindingContext(Element child, Object context)
at Microsoft.Maui.Controls.Element.<OnBindingContextChanged>b__82_0(BindableObject child, Object bc)
at Microsoft.Maui.Controls.BindableObjectExtensions.PropagateBindingContext[Element](BindableObject self, IEnumerable`1 children, Action`2 setChildBindingContext)
at Microsoft.Maui.Controls.Element.OnBindingContextChanged()
at Microsoft.Maui.Controls.VisualElement.OnBindingContextChanged()
at Microsoft.Maui.Controls.View.OnBindingContextChanged()
at Microsoft.Maui.Controls.BindableObject.SetInheritedBindingContext(BindableObject bindable, Object value)
at Microsoft.Maui.Controls.Element.SetChildInheritedBindingContext(Element child, Object context)
at Microsoft.Maui.Controls.TemplatedPage.SetChildInheritedBindingContext(Element child, Object context)
at Microsoft.Maui.Controls.Element.<OnBindingContextChanged>b__82_0(BindableObject child, Object bc)
at Microsoft.Maui.Controls.BindableObjectExtensions.PropagateBindingContext[Element](BindableObject self, IEnumerable`1 children, Action`2 setChildBindingContext)
at Microsoft.Maui.Controls.Element.OnBindingContextChanged()
at Microsoft.Maui.Controls.VisualElement.OnBindingContextChanged()
at Microsoft.Maui.Controls.Page.OnBindingContextChanged()
at Microsoft.Maui.Controls.ContentPage.OnBindingContextChanged()
at Microsoft.Maui.Controls.BindableObject.BindingContextPropertyChanged(BindableObject bindable, Object oldvalue, Object newvalue)
at Microsoft.Maui.Controls.BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, Object value, Boolean currentlyApplying, SetValueFlags attributes, Boolean silent)
at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes)
at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value, Boolean fromStyle, Boolean checkAccess)
at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value)
at Microsoft.Maui.Controls.BindableObject.set_BindingContext(Object value)
at OIL.ISA.Views.SettingsPage..ctor()
at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object , Object[] , Boolean )
Exception_EndOfInnerExceptionStack
at ObjCRuntime.Runtime.ThrowException(IntPtr )
at UIKit.UIApplication.UIApplicationMain(Int32 , String[] , IntPtr , IntPtr )
at UIKit.UIApplication.Main(String[] , Type , Type )
at OIL.ISA.Platforms.iOS.Program.Main(String[] args)
Unhandled managed exception: Arg_TargetInvocationException (System.Reflection.TargetInvocationException)
at ObjCRuntime.Runtime.ThrowException(IntPtr )
at UIKit.UIApplication.UIApplicationMain(Int32 , String[] , IntPtr , IntPtr )
at UIKit.UIApplication.Main(String[] , Type , Type )
at OIL.ISA.Platforms.iOS.Program.Main(String[] args)
(System.InvalidProgramException)
at Microsoft.Maui.Controls.Internals.TypedBinding`2[[OIL.ISA.ViewModels.SettingsViewModel, OIL.ISA, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].ApplyCore(Object sourceObject, BindableObject target, BindableProperty property, Boolean fromTarget)
at Microsoft.Maui.Controls.Internals.TypedBinding`2[[OIL.ISA.ViewModels.SettingsViewModel, OIL.ISA, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[System.String, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].<…>
InvalidProgramException根据要求，这里有一些调试细节。视图模型是这样的：
public class SettingsViewModel : MainMenuPageViewModel {
public SettingsViewModel(ViewModelServices services, IPushNotificationsService pushNotificationsService, IDatabaseUploader databaseUploader, ISecureStorage secureStorage) : base(services) {
_pushNotificationsService = pushNotificationsService;
_databaseUploader = databaseUploader;
_databaseUploader.OnProgressChanged += OnDatabaseUploadProgressChanged;
_secureStorage = secureStorage;
Title = BaseApp.Settings;
PushNotificationsEnabled = pushNotificationsService.DeviceToken != null;
PushNotificationsEnabledMessage = PushNotificationsEnabled ? BaseApp.PushNotificationsEnabled : BaseApp.PushNotificationsNotEnabled;
Logout = new Command(DoLogout);
SendDatabase = new Command(UploadDatabase);
ShowPushNotificationDetails = new Command(ShowNotificationDetails);
using var context = new Context();
UserInformation = BaseApp.LoggedInAs + " " + LocalSettings.GetUsername(context);
UpdateSettingsInformation();
Settings.OnRefresh += (sender, e) => UpdateSettingsInformation();
}
private void UpdateSettingsInformation() {
StoreInformation = Settings.Store == null ? "" : Settings.Store.Number + " - " + Settings.Store.Name;
OnPropertyChanged(nameof(StoreInformation));
}
private void OnDatabaseUploadProgressChanged(object sender, ProgressChangedEventArgs e) {
Progress = e.ProgressPercentage / 100f;
}
private readonly IPushNotificationsService _pushNotificationsService;
private readonly IDatabaseUploader _databaseUploader;
private readonly ISecureStorage _secureStorage;
public string UserInformation { get; }
public string StoreInformation { get; private set; }
public bool PushNotificationsEnabled { get; }
public string PushNotificationsEnabledMessage { get; }
public string AppVersion => AppInfo.VersionString;
public ICommand Logout { get; }
public ICommand SendDatabase { get; }
public ICommand ShowPushNotificationDetails { get; }
...
}
以及页面本身
<?xml version="1.0" encoding="UTF-8" ?>
<ContentPage
xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:controls="clr-namespace:OIL.ISA.Controls"
xmlns:vm="clr-namespace:OIL.ISA.ViewModels"
xmlns:r="clr-namespace:OIL.ISA.Resources"
x:DataType="vm:SettingsViewModel"
x:Class="OIL.ISA.Views.SettingsPage"
Title="{Binding Title}"
Shell.NavBarIsVisible="{Binding NavBarIsVisible}">
<ContentPage.Content>
<AbsoluteLayout HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<Image AbsoluteLayout.LayoutFlags="All" AbsoluteLayout.LayoutBounds="0,0,1,1"
Source="background.jpg" Aspect="AspectFill" />
<StackLayout AbsoluteLayout.LayoutFlags="PositionProportional" AbsoluteLayout.LayoutBounds=".5,0" WidthRequest="320"
BackgroundColor="#D0FFFFFF" Spacing="16" Padding="16" Margin="0,16">
<Label Text="{Binding UserInformation}" HorizontalOptions="Center" />
<Label Text="{Binding StoreInformation}" HorizontalOptions="Center" />
<Button Style="{StaticResource SettingsButton}"
Text="{x:Static r:BaseApp.LogoutButton}"
Command="{Binding Logout}" />
<Button Style="{StaticResource SettingsButton}"
Text="{x:Static r:BaseApp.SendDatabaseButton}"
Command="{Binding SendDatabase}" />
<StackLayout Orientation="Horizontal">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding ShowPushNotificationDetails}" />
</StackLayout.GestureRecognizers>
<CheckBox IsChecked="{Binding PushNotificationsEnabled}" VerticalOptions="Center" IsEnabled="False" />
<Label Text="{Binding PushNotificationsEnabledMessage}" VerticalOptions="Center" />
</StackLayout>
<Label Text="{Binding Path=AppVersion, StringFormat={x:Static r:BaseApp.Version}}"
HorizontalOptions="Center" />
</StackLayout>
<controls:BlockingActivityIndicator
AbsoluteLayout.LayoutFlags="All" AbsoluteLayout.LayoutBounds="0,0,1,1"
IsVisible="{Binding IsBusy}"
Message="{Binding BusyMessage}"
HasProgress="{Binding HasProgress}"
Progress="{Binding Progress}" />
</AbsoluteLayout>
</ContentPage.Content>
</ContentPage>
（但正如你所看到的，我已经找到了答案，我只需要在某个地方记录它，以防其他人遇到它。无论你相信与否，两个月后，在另一个视图中，这发生在我自己身上应用程序中的模型。这是现在 Google 中的第三个热门，我希望这样有用）
原来我的同事使用Resharper分析代码，它检测到ViewModel属性之一：
public string AppVersion => AppInfo.VersionString;
可以更改为
staticpublic static string AppVersion => AppInfo.VersionString;
这并没有在 Android 或 iOS 模拟器中造成任何问题，但直到很久以后在 iPad 上测试发行版本时才被发现。再次使其成为实例属性修复了错误。