Xamarin Android和Dependecy注入

Question

I develop an Android application with Xamarin. Suppose I have an Activity and it depends on some interface:

interface IFoo
{
    // methods
}

public class Foo : IFoo
{
    private readonly IBar _bar;

    public Foo(IBar bar)
    {
        _bar = bar;
    }

    // methods implementation
}
// dependency injection somewhere in Application class
var container = new UnityContainer();
container.RegisterType<IFoo, Foo>();   

public class MyActivity : Activity
{
    // it's incorrect constructor and this code will not be compiled
    public MyActivity(IFoo foo)
    {
        _foo = foo;
    }

    private readonly IFoo _foo;
} 

I would like to inject instance of IFoo in MyActivity's constructor but as you know it is impossible to create constructor with parameters. How could I pass initialized instance of IFoo with all its dependencies to MyActivity? I use Unity as Dependency Injection framework (but I can change it).

Answer 1

In you app class define:

public static UnityContainer container { get; private set; }

var container = new UnityContainer();

register your interface

container.RegisterType<IFoo, Foo>();   

and resolve as below

var myFoo = container.Resolve<IFoo>()

Note: Don't forget to add the namespace using Microsoft.Practices.Unity;