停止/抑制ObservableCollection.oncollectionChanged事件

Question

我添加了类

public class ObservableCollectionEx<T> : ObservableCollection<T>
{
    public bool SuppressEvents { get; set; } = true;

    public ObservableCollectionEx(): base() {}
    public ObservableCollectionEx(IEnumerable<T> collection): base(collection){}
    public ObservableCollectionEx(List<T> list): base(list){}

    public void RaiseCollectionChangedEvent()
    {
        SuppressEvents = false;

        this.OnPropertyChanged(new PropertyChangedEventArgs("Count"));
        this.OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
        this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
    }

    protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
    {
        if (!SuppressEvents)
            base.OnCollectionChanged(e);
    }
}

ViewModel

public ObservableCollectionEx<MyModel> myCollection = new ObservableCollectionEx<MyModel>();

Method1()
{
   myCollection.SuppressEvents = true;
   //some changes in Obs Collection.
   // some add/remove/insert operations on collection
   myCollection.RaiseCollectionChangedEvent(); // works
}

Method2()
{
   myCollection.SuppressEvents = true;
   //some changes in Obs Collection.
   // some add/remove/insert operations on collection
   myCollection.RaiseCollectionChangedEvent(); // breaks
}

，在ViewModel中，我通过调用raisecollectionChangedEvent方法来更改之前和更改后通过对变量进行切换来抑制事件。它在某些情况下正在工作。在某些人中，它引发了一个无效的指针例外。我无法观察导致例外的原因。

ps 错误

信息 对象引用未设置为对象的实例

stacktrace 安卓： in Xamarin.forms.platform.android.gridlayoutspansizelookup.getSpansize（system.int32位置）[0x00000] [0x00000] [0x00000] [0x00000] [\ a \ a \ a \ a \ s \ s \ xamarin.forms.platform.android \ android \ android \ collectionView \ cluctionView \ grid gridlayoutspansizelookup.ccs：18 at AndroidX.RecyclerView.Widget.GridLayoutManager+SpanSizeLookup.n_GetSpanSize_I (System.IntPtr jnienv, System.IntPtr native__this, System.Int32 position) [0x00008] in D:\a\1\s\generated\androidx.recyclerview.recyclerview\obj\ Release \ monoandroid9.0 \生成\ src \ androidx.recyclerview.widget.gridlaylayoutmanager.cs：510

ios：ios： in Xamarin.forms.platform.ios.itemsviewController 1 [titemsview] .updateTemplatedCell（xamarin.forms.platform.ios.templeatedcell.templeatedcell cell，Foundation.nsIndEdpath Indexpath Indexpath in d：\ a \ a \ 1 \ 1 \ a \ 1 \ 1 \ s \ xamarin.forms.platform.ios \ collectionView \ itemsViewController.cs：278 at xamarin.forms.platform.ios.itemsviewController 1 [titemsview] [titemsview] .createmeAsememememementCell（Foundation.nsIndexpath Indexpath Indexpath Indexpath）[0x0007B] a \ 1 \ s \ xamarin.forms.platform.ios \ collectionView \ itemsViewController.cs：619