MeadowApp.cs

using Meadow;
using Meadow.Devices;
using System.Threading.Tasks;

namespace ResolverServices;

public class MeadowApp : App<F7FeatherV2>
{
    private bool _useMock = false; // change this value to either output to the red LED or to a console message
    private bool _useConstructorInjection = true; // change this value to how injection can either use the contrsuctor or a public settable property

    public override Task Initialize()
    {
        // manually create an object and put it into the DI container
        var outputService = new FeatherV2OutputService(Device);
        // register it as the interface, not concrete type
        Resolver.Services.Add<IOutputService>(outputService);

        // this check could be from an app config setting, or even a digital input
        if (_useMock)
        {
            // let the resolver create a service for us
            // the created instance of MockService will get registered as IService
            Resolver.Services.Create<MockService, IService>();
        }
        else
        {
            // let the resolver create a service for us - this will inject the IOutputService in the constructor for us
            // the created instance of MyBasicService will get registered as IService
            if (_useConstructorInjection)
            {
                Resolver.Services.Create<InjectedConstructorService, IService>();
            }
            else
            {
                Resolver.Services.Create<InjectedPropertyService, IService>();
            }

        }

        return Task.CompletedTask;
    }

    public override async Task Run()
    {
        var state = true;

        // retrieve the service by registered type
        var service = Resolver.Services.Get<IService>();

        while (true)
        {
            service.SetOutputState(state);
            state = !state;
            await Task.Delay(1000);
        }
    }
}