How do you create on Xamarin a function that does something differently depending on the platform?

问题

I'm new to Xamarin and I'm developing an App for Android, iOS and UWP. At the moment I want to do something that unfortunately works differently on every platform from a ViewModel that's called by the crossplatform Xamarin.forms.

How do I create a function or class from that ViewModel that runs different Platform specific code depending on the platform that currently build?

回答1:

There is a service called DependencyService which allows you to register multiple implementations of an interface and it automatically returns proper implementation based on current environment.

You define interface in your common project, e.g.:

public interface IPrinter
{
    void Print();
}

And in each project you create different implementation. You also have to mark it with [assembly(typeof(YOUR_CLASS_NAME))] attribute.

[assembly:Dependency(typeof(AndroidPrinter))]
namespace MyApp.Android
{
    public class AndroidPrinter : IPrinter
    {
        public class Print()
        {
        }
    }
}

Then in your common project, in ViewModel, you can call:

public void ViewModelFooMethod()
{
    DependencyService.Get<IPrinter>().Print();
}

More about it here

回答2:

This should be your if else statement in your ViewModel class based on Platform. You can append one more else block that would be default for UWP

if (Device.RuntimePlatform == Device.iOS)
{
    //ios
}
else if (Device.RuntimePlatform == Device.Android)
{
    //android
}

One more way is there to get it is by using Xam.Plugin.DeviceInfo package from NuGet Package manager. Import

using Plugin.DeviceInfo;

Get Platform info like this

CrossDeviceInfo.Current.Platform.ToString();

来源：https://stackoverflow.com/questions/53153603/how-do-you-create-on-xamarin-a-function-that-does-something-differently-dependin

标签

android

ios

Xamarin

xamarin.forms

uwp