MvxBind CheckedChange SwitchCompat

Question

我遇到了將我的Android.Support.V7.Widget.SwitchCompat綁定到我的視圖模型（Mvvmcross是我正在使用的框架）的問題 我的確和使用另一個對象上的點擊綁定完全相同，它工作得很好。

觀看視圖時，我發現了錯誤是如下：

12-21 10:32:06.459 I/MvxBind (22969): 42,82 Failed to create target binding for binding CheckedChange for OnCheckedChanged 
[0:] MvxBind:Warning: 42,82 Failed to create target binding for binding CheckedChange for OnCheckedChanged 

於開關我有量多次。

他們說可能不得不對鏈接器做一些事情，因爲反射魔術不包括東西。

這樣他們說你必須創建一個文件「LinkerPleaseInclude」以保存對你的switchcompat的引用。我是這樣做的，但仍然錯誤依然存在。

LinkerPleaseInclude

class LinkerPleaseInclude 
{ 
    public void Include(TextView text) 
    { 
     text.AfterTextChanged += (sender, args) => text.Text = "" + text.Text; 
     text.Hint = "" + text.Hint; 
    } 

    public void Include(CompoundButton cb) 
    { 
     cb.CheckedChange += (sender, args) => cb.Checked = !cb.Checked; 
     cb.Hint = "" + cb.Hint; 
    } 
    public void Include(SwitchCompat cb) 
    { 
     cb.CheckedChange += (sender, args) => cb.Checked = !cb.Checked; 
     cb.Hint = "" + cb.Hint; 
    } 
    public void Include(ICommand command) 
    { 
     command.CanExecuteChanged += (s, e) => { if (command.CanExecute(null)) command.Execute(null); }; 
    } 
    public void Include(CheckBox checkBox) 
    { 
     checkBox.CheckedChange += (sender, args) => checkBox.Checked = !checkBox.Checked; 
    } 
} 

我ViewLayout：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:local="http://schemas.android.com/apk/res-auto" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="@dimen/md_list_single_line_item_height" 
    android:gravity="center_vertical" 
    android:paddingLeft="@dimen/md_list_item_horizontal_edges_padding" 
    android:paddingRight="@dimen/md_list_item_horizontal_edges_padding"> 
    <android.support.v7.widget.SwitchCompat 
    android:id="@+id/mySwitch" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_alignParentRight="true" 
    android:layout_centerVertical="true" 
    local:MvxBind="Checked IsActive; Click OnSwitchClick; CheckedChange OnCheckedChanged" /> 
    <TextView 
    android:id="@+id/Name" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_alignParentLeft="true" 
    android:textColor="@color/md_text_dark_primary_87" 
    android:textSize="@dimen/md_list_item_primary_text" 
    local:MvxBind="Text Name"/> 
    <TextView 
    android:id="@+id/Kind" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_alignParentBottom="true" 
    android:layout_alignParentLeft="true" 
    android:textColor="@color/md_text_dark_secondary_54" 
    android:textSize="@dimen/md_list_item_secondary_text" 
    android:layout_below="@+id/Name" 
    local:MvxBind="Text Kind"/> 
</RelativeLayout> 

這種佈局的另一個佈局的孩子：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:local="http://schemas.android.com/apk/res-auto" 
    android:orientation="vertical" 
    android:layout_width="match_parent" 
    android:layout_height="@dimen/md_list_two_line_item_height" 
    android:paddingTop="?android:attr/actionBarSize" 
    android:fitsSystemWindows="true"> 
    <MvxClickableLinearLayout 
     android:id="@+id/animalSelectionsList" 
     android:layout_width="fill_parent" 
     android:layout_height="wrap_content" 
     android:orientation="vertical" 
     android:divider="@drawable/divider_horizontal" 
     android:showDividers="middle" 
     local:MvxBind="ItemsSource SelectionsList" 
     local:MvxItemTemplate="@layout/listitem_animal_selections" /> 
</LinearLayout> 

Answer 1

CheckedChange是一個事件，所以它不是一個公共財產。您不能直接在MvvmCross中綁定事件，除非您創建自己的目標綁定來處理此事件並公開命令。

這可能看起來像：

public class MvxCompoundButtonCheckedChangeBinding : MvxAndroidTargetBinding 
{ 
    private ICommand _command; 
    private IDisposable _checkedChangeSubscription; 
    private IDisposable _canExecuteSubscription; 
    private readonly EventHandler<EventArgs> _canExecuteEventHandler; 

    protected CompoundButton View => (CompoundButton)Target; 

    public MvxCompoundButtonCheckedChangeBinding(CompoundButton view) 
     : base(view) 
    { 
     _canExecuteEventHandler = OnCanExecuteChanged; 
     _checkedChangeSubscription = view.WeakSubscribe<CompoundButton, CompoundButton.CheckedChangeEventArgs>(nameof(view.CheckedChange), ViewOnCheckedChangeClick); 
    } 

    private void ViewOnCheckedChangeClick(object sender, CompoundButton.CheckedChangeEventArgs args) 
    { 
     if (_command == null) 
      return; 

     if (!_command.CanExecute(null)) 
      return; 

     _command.Execute(view.Checked); 
    } 

    protected override void SetValueImpl(object target, object value) 
    { 
     _canExecuteSubscription?.Dispose(); 
     _canExecuteSubscription = null; 

     _command = value as ICommand; 
     if (_command != null) 
     { 
      _canExecuteSubscription = _command.WeakSubscribe(_canExecuteEventHandler); 
     } 
     RefreshEnabledState(); 
    } 

    private void RefreshEnabledState() 
    { 
     var view = View; 
     if (view == null) 
      return; 

     var shouldBeEnabled = false; 
     if (_command != null) 
     { 
      shouldBeEnabled = _command.CanExecute(null); 
     } 
     view.Enabled = shouldBeEnabled; 
    } 

    private void OnCanExecuteChanged(object sender, EventArgs e) 
    { 
     RefreshEnabledState(); 
    } 

    public override MvxBindingMode DefaultMode => MvxBindingMode.OneWay; 

    public override Type TargetType => typeof(ICommand); 

    protected override void Dispose(bool isDisposing) 
    { 
     if (isDisposing) 
     { 
      _checkedChangeSubscription?.Dispose(); 
      _checkedChangeSubscription = null; 

      _canExecuteSubscription?.Dispose(); 
      _canExecuteSubscription = null; 
     } 
     base.Dispose(isDisposing); 
    } 
} 

然後，你需要在FillTargetFactories覆蓋註冊在你Setup.cs：

registry.RegisterCustomBindingFactory<View>("MyCheckedChange", 
    view => new MvxCompoundButtonCheckedChangeBinding(view)); 

然後，你可以綁定MyCheckedChange你的命令。