如何将对象传递给Xamarin Forms自定义渲染器? [英] How to pass in an object to a Xamarin Forms custom renderer?

问题描述

如何将某个对象的实例传递给Xamarin表单custom render?

How can I pass an instance of some object, to a Xamarin Forms custom render?

这是自定义渲染器...

this is the custom renderer...

public class LoginPageRenderer : PageRenderer
{
    public override void ViewDidAppear (bool animated)
    {
        ....
    }
}

这就是我想要做的....(注意已添加了ctor ...)

and this is what I want to do.... (notice the ctor has been added ...)

public class LoginPageRenderer : PageRenderer
{
    private SomeFoo _someFoo;

    public LoginPageRenderer(MyFoo someFoo)
    {
        _someFoo = someFoo;
    }

    public override void ViewDidAppear (bool animated)
    {
        ....
    }
}

最后，这是调用此视图的地方(在代码的其他部分).

Finally, this is where this view is called (in some other part of the code).

await _navigationPage.Navigation.PushModalAsync(new LoginPage());

推荐答案

如果在LoginPage对象中定义了可公开访问的属性，则可以使用Element.NameOfYourProperty语法在Renderer中引用该属性.

If you define a publicly accessible property in your LoginPage object you can reference it in the Renderer using Element.NameOfYourProperty syntax.

示例代码...

LoginPage.cs (在您的PCL公共项目中).

LoginPage.cs (in your PCL common project).

namespace Foo
{
    public class LoginPage : ContentPage
    {
        private readonly Foo _foo;

        public LoginPage(Foo foo)
        {
            _foo = foo;
        }

        public Foo Foo { get; private set; }
    }
}

LoginPageRenderer.cs (在您的iOS项目中)

LoginPageRenderer.cs (in your iOS project)

[assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))]

namespace Foo.iOS
{
    public class LoginPageRenderer : PageRenderer
    {
        private Foo Foo
        {
            get
            {
                var loginPage = Element as LoginPage;
                return loginPage == null
                    ? null
                    : loginPage.Foo; 
            }
        }

        public override void ViewDidAppear (bool animated)
        {
            if (string.IsNullOrWhitespace(Foo.SecretName))
            { ... }

            ...
        }
    }
}

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