我尝试了很多组合来测试LoadData中的代码功能。

第一次加载页面时，LoadData函数被调用。稍后用户更改导致 LoadData 的日期函数被再次调用。这次出现了下面引用的错误。如果我注释了 Collection = programs 行，代码就没有问题。

即使程序在第二次执行函数时有 0 个项目，也会出现问题。

public async Task LoadData (DateTime day)
        { 
            this.day = day;

            var programs = await new ECEProgramLogic().GetGrouppedProgram(day.Date, actionNameType);

            Collection = programs; 
        }

    private ObservableCollection<GroupViewModel<object>> collection;
        public ObservableCollection<GroupViewModel<object>> Collection 
        {
            get
            {
                return collection;
            }
            set
            {
                collection = value;
                Banner = new NoDataBannerViewModel<GroupViewModel<object>>(value, AppResources.NoDataToShow);
                OnPropertyChanged(nameof(Collection));
            }
        }

Specified argument was out of the range of valid values. Parameter name: index

来自 Xamarin 的堆栈跟踪:

at Xamarin.Forms.ListProxy.get_Item (System.Int32 index) [0x0000b] in D:\agent_work\1\s\Xamarin.Forms.Core\ListProxy.cs:127 at Xamarin.Forms.ListProxy.System.Collections.IList.get_Item (System.Int32 index) [0x00000] in D:\agent_work\1\s\Xamarin.Forms.Core\ListProxy.cs:444 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].get_Item (System.Int32 index) [0x00008] in <afec569c85894ae9a18371a2fecd2d37>:0 at Xamarin.Forms.Platform.iOS.ListViewRenderer+ListViewDataSource.HeaderViewDisplayingEnded (UIKit.UITableView tableView, UIKit.UIView headerView, System.nint section) [0x0001f] in <82f6100a289642ae988dc0d85a373bef>:0 at (wrapper managed-to-native) ObjCRuntime.Messaging.void_objc_msgSend(intptr,intptr) at UIKit.UITableView.ReloadData () [0x00008] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.9.1.24/src/Xamarin.iOS/UIKit/UITableView.g.cs:792 at Xamarin.Forms.Platform.iOS.ListViewRenderer.UpdateItems (System.Collections.Specialized.NotifyCollectionChangedEventArgs e, System.Int32 section, System.Boolean resetWhenGrouped) [0x002b8] in <82f6100a289642ae988dc0d85a373bef>:0 at Xamarin.Forms.Platform.iOS.ListViewRenderer.OnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00000] in <82f6100a289642ae988dc0d85a373bef>:0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x0000a] in :0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].GroupedReset () [0x000b6] in <afec569c85894ae9a18371a2fecd2d37>:0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].OnCollectionChangedGrouped (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00459] in :0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].OnProxyCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e, System.Boolean fixWindows) [0x00008] in <afec569c85894ae9a18371a2fecd2d37>:0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].OnProxyCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00000] in :0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].OnItemsSourceChanged (System.Boolean fromGrouping) [0x00069] in <afec569c85894ae9a18371a2fecd2d37>:0 at Xamarin.Forms.Internals.TemplatedItemsList2[TView,TItem].BindableOnPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00020] in :0 at (wrapper delegate-invoke) .invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs) at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x0000a] in D:\agent_work\1\s\Xamarin.Forms.Core\BindableObject.cs:146 at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\agent_work\1\s\Xamarin.Forms.Core\Element.cs:401 at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00107] in D:\agent_work\1\s\Xamarin.Forms.Core\BindableObject.cs:602 at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\agent_work\1\s\Xamarin.Forms.Core\BindableObject.cs:399 at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, System.Boolean fromTarget) [0x001f9] in D:\agent_work\1\s\Xamarin.Forms.Core\BindingExpression.cs:172 at Xamarin.Forms.BindingExpression.Apply (System.Boolean fromTarget) [0x0003e] in D:\agent_work\1\s\Xamarin.Forms.Core\BindingExpression.cs:56 at Xamarin.Forms.BindingExpression+BindingExpressionPart.b__47_0 () [0x00000] in D:\agent_work\1\s\Xamarin.Forms.Core\BindingExpression.cs:557 at Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.9.1.24/src/Xamarin.iOS/Foundation/NSAction.cs:163 at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr) at UIKit.UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) [0x00005] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.9.1.24/src/Xamarin.iOS/UIKit/UIApplication.cs:79 at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x00038] in /Library/Frameworks/Xamarin.iOS.framework/Versions/11.9.1.24/src/Xamarin.iOS/UIKit/UIApplication.cs:63 at Tux.iOS.Application.Main (System.String[] args) [0x00001] in /Users/simon/Documents/AimyPlus/EceAdmin/Tux/Tux.iOS/Main.cs:17

> Xamarin.Android
Version: 8.2.0.16 (Visual Studio Community)
Android SDK: /Users/simon/Library/Developer/Xamarin/android-sdk-macosx
    Supported Android versions:
        6.0 (API level 23)
        7.1 (API level 25)
        8.0 (API level 26)

SDK Tools Version: 25.2.5
SDK Platform Tools Version: 25.0.5
SDK Build Tools Version: 25.0.3

Java SDK: /usr
java version "1.8.0_101"
Java(TM) SE Runtime Environment (build 1.8.0_101-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode)

Android Designer EPL code available here:
https://github.com/xamarin/AndroidDesigner.EPL

Xamarin Inspector
Version: 1.4.0
Hash: b3f92f9
Branch: master
Build date: Fri, 19 Jan 2018 22:00:34 GMT
Client compatibility: 1

Apple Developer Tools
Xcode 9.2 (13772)
Build 9C40b

Xamarin.Mac
Version: 4.2.1.28 (Visual Studio Community)

Xamarin.iOS
Version: 11.9.1.24 (Visual Studio Community)
Hash: f62de472
Branch: xcode9.3
Build date: 2018-03-29 19:30:53-0400

最佳答案

这是更新后的 Xamarin.Forms 2.51444934 的问题。它发生在做分组 ListView 时。为了解决:

ListView.HasUnevenRows = false;
ListView.IsGroupingEnabled = false;
((ObservableCollection<T>)listView.ItemsSource).Clear();
ListView.HasUnevenRows = true;
ListView.IsGroupingEnabled = true;

在替换新的数据集合之前放置类似的代码。问题将得到解决。

关于ios - Xamarin Form : ListView causing Specified argument was out of the range of valid values. 参数名称:index，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49976292/