如何使用mvvmcross双向绑定到UITextView控件? [英] How do I do two-way binding to a UITextView control using mvvmcross?

问题描述

我有一个使用XCode(它是XIB)创建的简单视图.它由两个UITextView控件和一个UIButton组成.我已经将UITextView控件公开为Outlets，并为其指定了名称.一切在我的View.designer.cs文件中看起来都很好.

I have a simple view I created using XCode (it's a XIB). It consists of two UITextView controls and a UIButton. I've exposed the UITextView controls as Outlets and given them names. Everything looks good in my View.designer.cs file.

我正在使用以下语法创建绑定:

I'm creating my binding using this syntax:

        this.AddBindings(
            new Dictionary<object, string>()
            {
                {lastname, "{'Text':{'Path':'LastName','Mode':'TwoWay'}}"},
                {uservin, "{'Text':{'Path':'CarVIN','Mode':'TwoWay'}}"}

            });

当我从姓氏UITextView移到uservin UITextView时，我希望我的视图模型中的SETTER被调用，但没有被调用.当我单击按钮并检查ViewModel上两个文本属性的值时，它们都为空.

When I move from the lastname UITextView to the uservin UITextView I expect the SETTER in my viewmodel to get called, but it doesn't. When I click the button and check the value of the two text properties on my ViewModel, they are both null.

有人知道我做错了吗?我将在周二发布一个快速演示，所有其他平台都可以很好地运行，但是似乎无法克服这个问题.

Does anybody know what I've done wrong? I've got a quick demo due on Tuesday and have all other platforms working beautifully, but just can't seem to get past this issue.

干杯

/j

推荐答案

我认为问题是您使用的是UITextView实例...但是mvvmcross vnext仅对UITextField元素提供2向绑定.

I think the problem will be that you are using UITextView instances... but mvvmcross vnext only ships with 2-way binding for UITextField elements.

要将UITextView 2向绑定添加到较旧的mvvmcross版本:

To add the UITextView 2-way binding to an older mvvmcross version:

1. 添加自定义目标绑定类-类似于v3中的类:在Setup.cs期间使用以下代码注册它:

   Register it during Setup.cs with code like:

   protected override void FillTargetFactories(IMvxTargetBindingFactoryRegistry registry)
   {
       base.FillTargetFactories(registry);
   
       registry.RegisterFactory(new MvxSimplePropertyInfoTargetBindingFactory(typeof(MvxUITextViewTextTargetBinding), typeof(UITextView), "Text");
   }
   

---

或者(但可能不在您的直接演示之前)，您可以考虑更新到v3 beta版本.

---

Alternatively (but maybe not before your immediate demos), you could consider updating to the v3 beta release.

顺便说一句，现在通常使用"swiss"绑定语法是执行此操作的常规方法:

Incidentally, using the 'swiss' binding syntax is generally now the normal way to do this:

    this.AddBindings(
        new Dictionary<object, string>()
        {
            {lastname, "Text LastName"},
            {uservin, "Text CarVIN"}
        });

...和TwoWay绑定是大多数非Windows MvvmCross绑定的默认绑定.

... and TwoWay binding is the default for most non-Windows MvvmCross bindings.

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