E.newelement和Control之间的区别？
想为xamarin.forms.forms.pooks.pookers.s.pookers.s.pookers.s.pooks.s.pooks.s.pooks.spicks.spicks.spicks.spicks.spicks.s.pookers.s.pooks.spicks.spicks.spicks.spicks.spicks.spickersont。
protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
因此，在制作自定义渲染器时，您可以在Overriden onelementChanged（）函数中进行大部分工作。我 第二个似乎是从ViewRenderer继承的（在我的情况下是Pickerrenderer）。我也不完全了解E.Oldelement的作用，也许是对我上一个自定义选择器的引用？谢谢。
So when making a custom renderer , you do most of your work inside the overriden OnElementChanged() function.I want to make a custom renderer for the Xamarin.Forms.Picker control:
protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
what is here the difference between e.NewElement and Control?The second one seems to be inherited from ViewRenderer(PickerRenderer in my case).I also don't quite understand what e.OldElement does, maybe the reference to my last custom Picker? Thanks.
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控制（this.control）是平台控件。例如，在Android上，它是android.views.views.view的子类。element（this.element）是指Xamarin形式的跨平台元素/视图。它是xamarin.forms.view的子类。e.newelement始终与this.Element相同。e.oldelement是此自定义渲染器附加的先前值。当创建渲染器时，它将是null。onelementChanged可以再次调用，e.oldelement是即将消失的XF元素。在这种情况下，e.NewElement是null。重要：在
中，onelementChanged，始终检查e.NewElementisnull。。 （或在“走开”/处置时需要做任何“清理”代码，如果您需要做某事。）Control(this.Control) is the PLATFORM control. E.g. on Android, it is a subclass ofAndroid.Views.View.Element(this.Element) refers to the XAMARIN FORMS cross-platform element/view. It is a subclass ofXamarin.Forms.View.e.NewElementis always identical tothis.Element.e.OldElementis the previous value that was attached to this custom renderer. It will benullwhen the renderer is created.OnElementChangedmight be called again, withe.OldElementbeing the XF element that is going away. In this case,e.NewElementisnull.IMPORTANT: In
OnElementChanged, always check whethere.NewElementisnull. If it is, do nothing. (Or call any "cleanup" code, if you need to do something when "going away"/disposing.)